WebGPU

W3C 候选推荐草案,

关于本文档的更多信息
本版本:
https://www.w3.org/TR/2025/CRD-webgpu-20250711/
最新发布版本:
https://www.w3.org/TR/webgpu/
编辑草案:
https://gpuweb.github.io/gpuweb/
先前版本:
历史:
https://www.w3.org/standards/history/webgpu/
反馈:
public-gpu@w3.org 邮件主题请写为 “[webgpu] …消息主题…” (存档)
GitHub
编辑者:
(Google)
(Google)
(Mozilla)
前任编辑者:
(Apple Inc.)
(Mozilla)
(Apple Inc.)
参与:
提交问题 (开放问题)
测试套件:
WebGPU CTS

摘要

WebGPU 提供了一个 API,可用于在图形处理单元(GPU)上执行渲染与计算等操作。

本文件状态

本节描述了本文档在发布时的状态。当前 W3C 出版物和本技术报告的最新修订可在 W3C 标准与草案索引 查询。

欢迎对本规范提出反馈和意见。建议优先通过 GitHub Issues 参与讨论。你也可以向 GPU for the Web 工作组邮件列表 public-gpu@w3.org存档)发送评论。本草案突出了工作组仍需讨论的一些待决问题,目前尚未就其结果作出决定,包括其有效性。

本文档由 GPU for the Web 工作组推荐流程 作为候选推荐草案发布。为确保有充分的广泛评审机会,本文件将至少保持候选推荐状态至

工作组期望在至少两个已部署的浏览器中基于现代 GPU 系统 API 演示每项特性的实现。测试套件将用于编写实现报告。

作为候选推荐发布并不代表 W3C 及其成员的认可。候选推荐草案整合了工作组打算在后续推荐快照中包含的前一候选推荐的更改。

本文档可随时维护和更新,其中部分内容尚在完善中。

本文档由遵循 W3C 专利政策 的工作组编写。W3C 维护了与本组交付物相关的 专利公开列表,该页面也包括专利披露说明。个人如获知包含 必要权利要求 的专利,应依 W3C 专利政策第6节 披露相关信息。

本文档受 2023年11月3日 W3C 流程文档 管辖。

1. 引言

本节为非规范性内容。

图形处理单元(GPU)在个人计算领域中已成为实现丰富渲染和计算应用的关键。WebGPU 是一个为 Web 暴露 GPU 硬件能力的 API。该 API 从零开始设计,能够高效映射到(2014年之后的)原生 GPU API。WebGPU 与 WebGL 无关,也不直接针对 OpenGL ES。

WebGPU 将物理 GPU 硬件视为 GPUAdapter。它通过 GPUDevice 提供与适配器的连接,设备负责管理资源,并通过设备的 GPUQueue 执行命令。GPUDevice 可能拥有自己的高速存储器以供处理单元访问。GPUBufferGPUTexture 是由 GPU 内存支持的物理资源GPUCommandBufferGPURenderBundle 是用户录制命令的容器。GPUShaderModule 包含 着色器代码。其他资源如 GPUSamplerGPUBindGroup 用于配置 GPU 如何使用物理资源

GPU 通过 GPUCommandBuffer 编码的命令,通过 管线 执行,该管线是固定功能与可编程阶段的混合体。可编程阶段运行着色器,即专为 GPU 硬件设计的特殊程序。管线的大部分状态由 GPURenderPipelineGPUComputePipeline 对象定义。未包含在这些 管线对象中的状态,则在命令编码阶段通过如 beginRenderPass()setBlendConstant() 之类命令设置。

2. 恶意使用考量

本节为非规范性内容。 介绍了在 Web 上暴露此 API 所带来的风险。

2.1. 安全考量

WebGPU 的安全要求与 Web 一贯的要求相同,也是不可协商的。总体原则是:在所有命令到达 GPU 之前进行严格校验,确保页面只能操作自身数据。

2.1.1. 基于 CPU 的未定义行为

WebGPU 实现会将用户发起的工作量转换为目标平台特定的 API 命令。原生 API 规定了命令的有效用法(例如见 vkCreateDescriptorSetLayout),并且通常不保证不遵守有效用法规则时的任何结果。这被称为“未定义行为”,攻击者可以利用它访问非授权内存,或迫使驱动执行任意代码。

为禁止不安全用法,WebGPU 针对任意输入都定义了允许的行为范围。实现必须校验所有用户输入,只允许有效工作负载到达驱动。本规范规定了所有错误条件及其处理语义。例如,在 copyBufferToBuffer() 的 "source" 和 "destination" 同时指定同一缓冲区,且区间相交时,GPUCommandEncoder 会生成错误,且不会执行其它操作。

更多错误处理信息参见 § 22 错误与调试

2.1.2. 基于 GPU 的未定义行为

WebGPU 着色器 由 GPU 内部的计算单元执行。在原生 API 中,某些着色器指令可能在 GPU 上导致未定义行为。为应对这一点,WebGPU 严格定义了着色器指令集及其行为。当为 createShaderModule() 提供着色器时,WebGPU 实现必须在进行任何平台特定着色器转换或变换之前进行校验。

2.1.3. 未初始化数据

一般来说,分配新内存可能暴露系统上其它应用残留的数据。为避免此问题,WebGPU 在概念上会将所有资源初始化为零,尽管若实现检测到开发者已手动初始化内容时可跳过此步骤。这包括着色器内变量和共享工作组内存。

清除工作组内存的具体机制依平台而异。若原生 API 未提供清除机制,WebGPU 实现会先在所有调用中清空,再同步,然后继续执行开发者代码。

注:
资源在队列操作中被使用时,其初始化状态只有在操作入队时才能确定(而不是在命令缓冲区编码时)。因此,一些实现会在入队时执行非优化的延迟清除(如清除纹理,而不是将 GPULoadOp "load" 改为 "clear")。

因此,无论实现是否有性能损耗,所有实现应当在开发者控制台发出警告。

2.1.4. 着色器中的越界访问

着色器可以直接访问物理资源(如 "uniform" GPUBufferBinding),也可以通过纹理单元(为纹理坐标转换而设的固定功能硬件块)间接访问。WebGPU API 的校验只能保证所有着色器输入已提供且类型正确。如果未通过纹理单元访问,WebGPU API 无法保证数据访问不会越界。

为防止着色器访问非本应用 GPU 内存,WebGPU 实现可在驱动中启用“健壮缓冲区访问”模式,确保访问不会超出缓冲区界限。

或者,实现可在着色器代码中插入手动越界检查。此时,越界检查仅适用于数组索引,对结构体字段访问则无需手动检查,因为主机侧 minBindingSize 校验已覆盖。

若着色器尝试读取物理资源边界外的数据,实现可以:

  1. 返回资源边界内其他位置的值

  2. 返回值向量 "(0, 0, 0, X)",其中 X 可为任意值

  3. 部分丢弃绘制或调度调用

若着色器尝试写入物理资源边界外,实现可以:

  1. 写入资源边界内其他位置

  2. 丢弃写入操作

  3. 部分丢弃绘制或调度调用

2.1.5. 无效数据

从 CPU 向 GPU 上传 浮点数数据或在 GPU 上生成浮点数时,可能会出现不对应于有效数值的二进制表示(如无穷大或 NaN)。此时 GPU 行为取决于硬件对 IEEE-754 标准的实现精度。WebGPU 保证引入无效浮点数只会影响算术运算结果,不会有其他副作用。

2.1.6. 驱动漏洞

GPU 驱动程序和其他软件一样可能存在漏洞。攻击者可能利用驱动的错误行为访问非授权数据。为降低风险,WebGPU 工作组将与 GPU 厂商协作,将 WebGPU 一致性测试套件(CTS)集成到驱动测试流程中,类似 WebGL 的做法。WebGPU 实现应对已发现的部分漏洞有兼容性处理,并对无法绕过的已知漏洞驱动禁用 WebGPU。

2.1.7. 时序攻击

2.1.7.1. 内容时间线时序

WebGPU 不会向 JavaScript 暴露在 内容时间线上由 agentagent cluster 中共享的新状态。内容时间线状态如 [[mapping]] 仅在显式 内容时间线任务(如普通 JavaScript)中变化。

2.1.7.2. 设备/队列时间线时序

可写存储缓冲区和其他跨调用通信机制可能用于在队列时间线上构造高精度定时器。

可选的 "timestamp-query" 特性也为 GPU 操作提供高精度计时。为缓解安全和隐私风险,定时查询的值被对齐到较低精度:参见 current queue timestamp。特别注意:

2.1.8. Row hammer 攻击

Row hammer 是一类利用 DRAM 单元状态泄漏的攻击,可被用于 GPU。WebGPU 没有专门的防护措施,依赖于平台级解决方案,例如缩短内存刷新间隔。

2.1.9. 拒绝服务

WebGPU 应用可访问 GPU 内存和计算单元。WebGPU 实现可以限制应用可用的 GPU 内存,以保证其他应用的响应性。对于 GPU 处理时间,WebGPU 实现可以设置“看门狗”定时器,确保应用不会导致 GPU 无响应超过数秒。这些措施类似于 WebGL 所采用的策略。

2.1.10. 工作负载识别

WebGPU 提供对全局受限资源的访问,这些资源由同一台机器上不同程序(和网页)共享。应用可通过间接探测全局资源受限程度,进而推测其他网页正在进行的工作负载。这些问题与 Javascript 中的系统内存和 CPU 执行吞吐量类似。WebGPU 没有对此提供额外的缓解措施。

2.1.11. 内存资源

WebGPU 允许从机器全局内存堆(如 VRAM)进行可失败的分配。这使得应用可以通过尝试分配并观察分配失败情况,探测系统剩余可用内存(针对特定堆类型)。

GPU 内部一般有一个或多个(通常只有两个)所有运行应用共享的内存堆。当某个堆耗尽时,WebGPU 创建资源会失败。这是可观察到的,可能使恶意应用推测出其他应用使用了哪些堆,以及它们分配了多少。

2.1.12. 计算资源

如果一个站点与另一个站点同时使用 WebGPU,它可能会观察到处理某些工作的耗时增加。例如,持续向队列提交计算工作并跟踪完成时间,可能会发现其他任务也开始使用 GPU。

GPU 有多个可独立测试的部分,如算术单元、纹理采样单元、原子单元等。恶意应用可以检测某些单元的负载,并试图分析压力模式来猜测其他应用的工作负载。这与 Javascript 的 CPU 执行现实类似。

2.1.13. 能力滥用

恶意站点可能滥用 WebGPU 所暴露的能力,运行对用户或其体验无益、仅对站点有利的计算。例如隐蔽挖矿、密码破解或彩虹表计算。

无法针对这类 API 使用方式加以防范,因为浏览器无法区分有效负载和滥用负载。这是 Web 上所有通用计算能力(如 JavaScript、WebAssembly 或 WebGL)面临的普遍问题。WebGPU 只是让某些负载的实现更容易,或比 WebGL 更高效。

为缓解此类滥用,浏览器可对后台标签页的操作进行限速,可警告标签页资源占用过高,并可限制哪些上下文允许使用 WebGPU。

用户代理可基于启发式方法向用户发出高功耗警告,尤其在检测到潜在恶意使用时。如果实现此类警告,应将 WebGPU 使用纳入与 JavaScript、WebAssembly、WebGL 等相同的启发式中。

2.2. 隐私考量

There is a tracking vector here. WebGPU 的隐私考量与 WebGL 类似。GPU API 十分复杂,必须出于必要暴露设备能力的各个方面,以便开发者能够有效利用这些能力。一般的缓解方法是对潜在可识别信息进行归一化或分桶,并在可能的情况下强制行为一致。

用户代理不得暴露超过 32 种可区分配置或分桶。

2.2.1. 机器特有功能与限制

WebGPU 可以揭示底层 GPU 架构和设备结构的许多细节,包括可用的物理适配器、GPU 和 CPU 资源的多项限制(如最大纹理尺寸),以及可用的任何可选硬件专属能力。

用户代理没有义务暴露真实硬件限制,可以完全控制机器细节的暴露程度。减少指纹识别的一种策略是将所有目标平台归为少数几个分桶。总体来说,暴露硬件限制的隐私影响与 WebGL 相同。

默认限制值也被故意设置得足够高,以便大多数应用无需请求更高限制即可运行。所有 API 的使用都按请求限制进行校验,因此不会因意外而向用户暴露实际硬件能力。

2.2.2. 机器特有产物

和 WebGL 一样,可以观察到一些机器特有的光栅化/精度差异和性能差异。这涉及光栅化覆盖及模式、着色器阶段间 varyings 的插值精度、计算单元调度,以及更多执行相关特性。

通常,同一厂商的大多数或全部设备的光栅化和精度指纹是相同的。性能差异难以完全规避,但信号强度较低(如 JS 执行性能)。

对隐私要求高的应用和用户代理应采用软件实现以消除这类产物。

2.2.3. 机器特有性能

通过测量 GPU 上特定操作的性能也是区分用户的一个因素。即便计时精度较低,重复执行某一操作也能体现用户机器在特定负载下的快慢。这是常见的识别向量(WebGL 和 Javascript 皆有),但信号较低且难以完全规避。

WebGPU 计算管线让开发者可绕过固定功能硬件直接访问 GPU,这带来了独特设备指纹识别的额外风险。用户代理可通过将逻辑 GPU 调用与实际计算单元解耦来降低此风险。

2.2.4. 用户代理状态

本规范未为源定义任何额外用户代理状态。但预期用户代理会对 GPUShaderModuleGPURenderPipelineGPUComputePipeline 等高开销编译结果进行缓存。这些缓存有助于提升 WebGPU 应用首次访问后的加载速度。

对规范而言,这些缓存与极快编译无异,但应用可以轻易测量 createComputePipelineAsync() 的耗时。这可能导致跨源信息泄露(如“用户是否访问过包含特定着色器的站点”),因此用户代理应遵循 存储分区最佳实践。

系统的 GPU 驱动也可能有自己的着色器和管线编译缓存。用户代理可在可能的情况下禁用该缓存,或为着色器添加分区数据,使驱动将其视为不同对象。

2.2.5. 驱动漏洞

安全考量中提到的问题外,驱动漏洞还可能导致行为差异,成为区分用户的手段。此处可采用安全考量中提及的缓解措施,如与 GPU 厂商协作,在用户代理中实现已知问题的兼容处理。

2.2.6. 适配器标识符

WebGL 实践表明,开发者有合理需求识别其代码运行的 GPU,以便创建和维护健壮的 GPU 内容。例如识别有已知驱动漏洞的适配器,以便规避或避免在某些硬件上使用表现不佳的特性。

但暴露适配器标识符自然会增加指纹识别信息量,因此有必要限制适配器识别的精度。

可以采取多项缓解措施以平衡内容健壮性与隐私保护。首先,用户代理可通过主动识别和规避已知驱动问题,减少开发者负担,就像浏览器开始用 GPU 以来所做的一样。

默认暴露适配器标识符时应尽量宽泛,只要有用即可。例如,可仅标识适配器厂商及架构而非具体型号。有时也可报告实际适配器的合理代理的标识符。

在需要完整详细适配器信息(如提交 bug 报告)时,可请用户同意向页面披露更多硬件信息。

最后,若用户代理认为合适(如增强隐私模式下),可完全不报告适配器标识符。

3. 基础

3.1. 约定

3.1.1. 语法速记

本规范中使用了如下语法速记:

.(点)语法,常见于编程语言。

短语“Foo.Bar”表示“值(或接口)FooBar 成员”。如果 Foo有序映射(ordered map)BarFoo 中未存在,则返回 undefined

短语“Foo.Bar提供”表示“Bar 成员存在映射Foo 中”。

?.(可选链)语法,借鉴自 JavaScript。

短语“Foo?.Bar”表示:“如果 FoonullundefinedBarFoo 中未存在,则为 undefined;否则为 Foo.Bar”。

例如,若 buffer 是一个 GPUBuffer,则 buffer?.\[[device]].\[[adapter]] 表示:“如果 buffernullundefined,则为 undefined;否则为 buffer\[[device]] 内部槽的 \[[adapter]] 内部槽。”

??(空值合并)语法,借鉴自 JavaScript。

短语“x ?? y”表示:“如果 x 不为 null 或 undefined,则为 x,否则为 y。”

槽支持属性(slot-backed attribute)

由同名内部槽支持的 WebIDL 属性。其可变性视规范而定。

3.1.2. WebGPU 对象

WebGPU 对象WebGPU 接口内部对象组成。

WebGPU 接口定义了WebGPU 对象的公共接口和状态。它可在其创建的内容时间线上使用,此时它是 JavaScript 暴露的 WebIDL 接口。

任何包含 GPUObjectBase 的接口都是 WebGPU 接口

内部对象跟踪WebGPU 对象设备时间线上的状态。所有对内部对象可变状态的读写都发生在单一有序的设备时间线步骤中。

WebGPU 对象上可定义以下特殊属性类型:

不可变属性(immutable property)

在对象初始化时设定的只读槽,可从任意时间线访问。

注:由于该槽不可变,实现可在多个时间线中保有副本,按需分配。不可变属性这样定义是为避免在规范中描述多个副本。

若命名为 [[带括号]],则是内部槽。
若命名为 不带括号,则是 WebGPU 接口readonly 槽支持属性

内容时间线属性(content timeline property)

仅可从对象创建的内容时间线访问的属性。

若命名为 [[带括号]],则是内部槽。
若命名为 不带括号,则是 WebGPU 接口槽支持属性

设备时间线属性(device timeline property)

跟踪内部对象状态,仅可从对象创建的设备时间线访问。设备时间线属性可为可变的。

设备时间线属性命名为 [[带括号]],为内部槽。

队列时间线属性(queue timeline property)

跟踪内部对象状态,仅可从对象创建的队列时间线访问。队列时间线属性可为可变的。

队列时间线属性命名为 [[带括号]],为内部槽。

interface mixin GPUObjectBase {
    attribute USVString label;
};
创建一个新的 WebGPU 对象GPUObjectBase parent,接口 TGPUObjectDescriptorBase descriptor)(其中 T 继承自 GPUObjectBase),请在内容时间线上执行以下步骤:
  1. deviceparent.[[device]]

  2. objectT 的新实例。

  3. 设置 object.[[device]]device

  4. 设置 object.labeldescriptor.label

  5. 返回 object

GPUObjectBase 具有如下不可变属性

[[device]],类型为device,只读

拥有该内部对象设备

对此对象内容的操作断言其运行在设备时间线上,并且设备是有效的。

GPUObjectBase 具有如下内容时间线属性

label类型为 USVString

开发者提供的标签,由实现自定义使用。可由浏览器、操作系统或其他工具用于帮助开发者识别底层内部对象。示例包括在 GPUError 消息、控制台警告、浏览器开发者工具和平台调试工具中显示标签。

注:
实现应当利用标签提升错误消息的可读性,用于标识 WebGPU 对象。

但这不必是标识对象的唯一方式:实现还应结合其他可用信息,尤其是在没有标签时。例如:

注:
labelGPUObjectBase 的属性。两个 GPUObjectBase “包装器”对象即使引用同一底层对象,其 label 状态也是完全独立的(如由 getBindGroupLayout() 返回时)。除非通过 JavaScript 设置,否则 label 属性不会变更。

这意味着一个底层对象可关联多个标签。本规范未定义标签如何传递到 设备时间线。标签的使用完全由实现自定义:错误消息可显示最近设置的标签、所有已知标签,或完全不显示标签。

属性类型为 USVString,因为某些用户代理可能将其传递给底层原生 API 的调试工具。

GPUObjectBase 具有如下设备时间线属性

[[valid]],类型为boolean,初始值为 true

若为 true,表示该内部对象可用。

注:
理想情况下,WebGPU 接口不应阻止其父对象(如拥有它的 [[device]])被垃圾回收。然而,这无法保证,因为某些实现可能需要强引用父对象。

因此,开发者应假定 WebGPU 接口在所有子对象被回收前可能不会被垃圾回收。这可能导致部分资源比预期保留更长时间。

如果需要可预测地释放分配的资源,应优先调用 destroy 方法(如 GPUDevice.destroy()GPUBuffer.destroy()),而不是依赖垃圾回收。

3.1.3. 对象描述符

对象描述符用于保存创建对象所需的信息,通常通过 GPUDevicecreate* 方法之一进行对象创建。

dictionary GPUObjectDescriptorBase {
    USVString label = "";
};

GPUObjectDescriptorBase 具有如下成员:

label类型为 USVString,默认值为 ""

GPUObjectBase.label 的初始值。

3.2. 异步性

3.2.1. 无效的内部对象与传染性无效

WebGPU 中的对象创建操作不会返回 Promise,但其本质上是异步的。返回的对象引用的是在设备时间线上被操作的内部对象。多数在设备时间线上发生的错误不会通过异常或拒绝抛出,而是通过关联设备上生成的 GPUError 进行传递。

内部对象可以是有效无效无效对象不会在之后变为有效,但部分有效对象可以被使无效(invalidated)

如果对象无法被创建,则其从创建开始即为无效。例如,对象描述符未能描述出有效对象,或者没有足够内存分配资源时会发生此情况。如果从另一个无效对象创建对象(例如对无效的 GPUTexture 调用 createView()),也会如此。这类情况称为传染性无效

大多数类型的内部对象在创建后不会变为无效,但仍可能变得不可用,例如其所属设备丢失destroyed,或对象处于特殊内部状态(如缓冲区状态“destroyed”)。

部分类型的内部对象在创建后可以变为无效;具体包括设备适配器GPUCommandBuffer,以及命令/通道/捆绑编码器。

给定 GPUObjectBase object,若 object.[[valid]]true,则为有效
给定 GPUObjectBase object,若 object.[[valid]]false,则为无效
给定 GPUObjectBase object,若满足以下设备时间线步骤的所有要求,则其可与 targetObject 一同使用(valid to use with)
使无效(invalidate) GPUObjectBase object,请在设备时间线上执行以下步骤:
  1. object.[[valid]] 设为 false

3.2.2. Promise 顺序

WebGPU 中有若干操作会返回 promise。

WebGPU 不保证这些 promise 的 settle(resolve 或 reject)顺序,除非有如下例外:

应用不得依赖于其它 promise 的 settle 顺序。

3.3. 坐标系统

渲染操作使用如下坐标系统:

注:WebGPU 的坐标系统与 DirectX 图形管线中的坐标系统一致。

3.4. 编程模型

3.4.1. 时间线

WebGPU 的行为以“时间线”为单位进行描述。每个操作(以算法定义)都发生在某个时间线上。时间线明确了操作的顺序,以及哪些状态可被哪些操作访问。

注: 这种“时间线”模型反映了浏览器引擎多进程模型(如“内容进程”和“GPU 进程”)的约束,也体现了许多实现中 GPU 作为独立执行单元的现实。实现 WebGPU 并不要求时间线并行执行,因此不要求多进程,甚至不要求多线程。(但如 获取上下文图像内容副本 这类需同步阻塞其它时间线完成的情况,仍需支持并发。)

内容时间线

与 Web 脚本的执行相关。包括本规范描述的所有方法调用。

要从 GPUDevice device 的操作向内容时间线派发步骤,可通过 为 GPUDevice 排队全局任务

设备时间线

与用户代理发起的 GPU 设备操作相关。包括适配器、设备、GPU 资源与状态对象的创建,这些操作从用户代理控制 GPU 的部分看通常是同步的,但可在独立的操作系统进程中运行。

队列时间线

与 GPU 计算单元上操作的执行相关。包括实际在 GPU 上运行的绘制、拷贝和计算任务。

时间线无关

可以与上述任意时间线关联。

如仅操作不可变属性或调用步骤传入的参数,则可派发到任意时间线。

以下展示了与各时间线关联的步骤和值的样式。该样式为非规范性内容,规范文本始终明确描述了其关联。
不可变值示例术语定义

可用于任意时间线。

内容时间线示例术语定义

仅可用于内容时间线

设备时间线示例术语定义

仅可用于设备时间线

队列时间线示例术语定义

仅可用于队列时间线

时间线无关的步骤如下所示。

不可变值示例术语的用法。

内容时间线上执行的步骤如下所示。

不可变值示例术语的用法。 内容时间线示例术语的用法。

设备时间线上执行的步骤如下所示。

不可变值示例术语的用法。 设备时间线示例术语的用法。

队列时间线上执行的步骤如下所示。

不可变值示例术语的用法。 队列时间线示例术语的用法。

本规范中,当返回值依赖于非内容时间线上发生的工作时,采用异步操作。API 以 promise 或事件的形式表现异步操作。

GPUComputePassEncoder.dispatchWorkgroups() 示例:
  1. 用户在 内容时间线 上通过 GPUComputePassEncoder 的方法编码 dispatchWorkgroups 命令。

  2. 用户调用 GPUQueue.submit(),将 GPUCommandBuffer 提交给用户代理,用户代理在 设备时间线 上调用操作系统驱动进行底层提交。

  3. GPU 调度器在 队列时间线 上将提交分派到实际计算单元执行。

GPUDevice.createBuffer() 示例:
  1. 用户填写 GPUBufferDescriptor,并用其创建 GPUBuffer,在 内容时间线 上发生。

  2. 用户代理在 设备时间线 上创建底层缓冲区。

GPUBuffer.mapAsync() 示例:
  1. 用户在 内容时间线 上请求映射 GPUBuffer,并获得一个 promise。

  2. 用户代理检查该缓冲区是否正被 GPU 使用,并设置提醒在使用结束后再次检查。

  3. 在 GPU 于 队列时间线 上使用完缓冲区后,用户代理将其映射到内存并 resolve 该 promise。

3.4.2. 内存模型

本节为非规范性内容。

一旦应用初始化过程中获取到 GPUDevice,我们可以将 WebGPU 平台描述为包含以下各层:

  1. 实现本规范的用户代理。

  2. 为该设备提供底层原生 API 驱动的操作系统。

  3. 实际的 CPU 和 GPU 硬件。

WebGPU 平台的每一层可能有不同类型的内存,用户代理在实现规范时需要加以考虑:

大多数物理资源分配在适合 GPU 计算或渲染的内存类型中。当用户需要向 GPU 提供新数据时,数据可能首先需要跨越进程边界,抵达与 GPU 驱动通信的用户代理部分。随后可能需要使数据对驱动可见,有时这需要拷贝到驱动分配的中转(staging)内存。最后,数据还可能需要传输到独立 GPU 内存中,并在内部转换为最适合 GPU 运算的布局。

所有这些转换都由用户代理的 WebGPU 实现负责完成。

注:上述示例描述了最坏情况,实际实现中可能无需跨越进程边界,或者能直接向用户暴露由驱动管理的内存(例如通过 ArrayBuffer),从而避免数据拷贝。

3.4.3. 资源用法

物理资源可以被GPU 命令内部用法使用:

输入(input)

为 draw 或 dispatch 调用提供输入数据的缓冲区。会保留内容。由缓冲区 INDEXVERTEXINDIRECT 允许。

常量(constant)

从着色器视角为常量的资源绑定。会保留内容。由缓冲区 UNIFORM 或纹理 TEXTURE_BINDING 允许。

存储(storage)

读/写存储资源绑定。由缓冲区 STORAGE 或纹理 STORAGE_BINDING 允许。

存储只读(storage-read)

只读存储资源绑定。会保留内容。由缓冲区 STORAGE 或纹理 STORAGE_BINDING 允许。

附件(attachment)

在渲染通道中作为读/写输出附件或仅写解决目标的纹理。由纹理 RENDER_ATTACHMENT 允许。

附件只读(attachment-read)

在渲染通道中作为只读附件的纹理。会保留内容。由纹理 RENDER_ATTACHMENT 允许。

子资源(subresource)指整个缓冲区或纹理子资源

某些内部用法彼此兼容。子资源(subresource)可以处于多个用法组合的状态。若列表 U 满足下列任一规则,则称其为兼容用法列表(compatible usage list)

强制要求用法仅可组合为兼容用法列表,使得 API 能够限制内存操作中的数据竞争出现时机。该属性使基于 WebGPU 的应用更容易无修改地在不同平台上运行。

示例:
在同一 GPURenderPassEncoder 中,将同一缓冲区既作为存储,又作为输入绑定,会导致该缓冲区的用法列表为非兼容用法列表
示例:
这些规则允许只读深度模板:单个深度/模板纹理可在渲染通道中同时以两种只读用法使用:
示例:
存储用法例外允许两种原本不被允许的情况:
示例:
附件用法例外允许一个纹理子资源多次作为附件使用。这对于允许 3D 纹理的不相交切片作为不同附件绑定到同一渲染通道很有必要。

但同一切片不得作为两个不同附件重复绑定;这由 beginRenderPass() 检查。

3.4.4. 同步机制

用法范围(usage scope)是一个从有序映射,其键为子资源,值为 列表<内部用法>。每个用法范围覆盖一组可能并发执行的操作,因此在该范围内对子资源的使用只能是兼容用法列表

若对于 scope 中每个 [subresource, usageList],usageList 均为兼容用法列表,则 用法范围 scope 通过用法范围校验
要向 使用作用域(usage scope) usageScope 添加(add)一个 子资源(subresource) subresource,并指定 usage(内部用法或一组内部用法usage
  1. 如果 usageScope[subresource] 不存在,则将其设为 []

  2. 追加 usageusageScope[subresource]。

要将 使用作用域(usage scope) A 合并(merge)使用作用域(usage scope) B
  1. 对于 A 中的每一项 [subresource, usage]:

    1. 添加(Add) subresourceB,并指定 usage usage

用法范围在编码期间被构建和校验:

用法范围如下:

注:拷贝命令为独立操作,不使用用法范围进行校验,其自身实现了防止自竞争的校验。

示例:
以下资源用法被计入用法范围

3.5. 核心内部对象

3.5.1. 适配器(Adapters)

适配器(adapter)标识系统上的 WebGPU 实现:既包括底层平台上的计算/渲染功能实例,也包括浏览器在该功能之上实现 WebGPU 的实例。

适配器通过 GPUAdapter 暴露。

适配器并不唯一代表底层实现:多次调用 requestAdapter() 每次都会返回不同的适配器对象。

每个 适配器对象只能用于创建一个 设备(device):一旦成功调用 requestDevice(),该适配器的 [[state]] 变为 "consumed"。此外,适配器对象可能在任何时刻过期(expire)

注: 这样保证应用在创建设备时能使用最新的系统状态来选择适配器。也让多种场景(如首次初始化、因适配器移除重初始化、因 GPUDevice.destroy() 测试重初始化等)行为保持一致,提高健壮性。

若适配器以显著性能换取更广兼容性、更可预测行为或更好的隐私,则可视为回退适配器(fallback adapter)。不是每个系统都必须提供回退适配器。

适配器具有如下不可变属性

[[features]],类型为 有序集合<GPUFeatureName>,只读

可用于在此适配器上创建设备的特性

[[limits]],类型为支持的限制,只读

可用于在此适配器上创建设备的最佳限制。每个限制值必须与支持的限制中该项的默认值相同或更好(better)。

[[fallback]],类型为 boolean,只读

true 时,表示该适配器是回退适配器

[[xrCompatible]],类型为 boolean

true 时,表示该适配器请求了与 WebXR 会话 兼容。

适配器具有如下设备时间线属性

[[state]],初始值为 "valid"
"valid"

适配器可用于创建设备。

"consumed"

适配器已被用于创建设备,不能再次使用。

"expired"

适配器因其他原因已过期。

使 GPUAdapter 过期,请在设备时间线上执行:
  1. adapter.[[adapter]].[[state]] 设为 "expired"

3.5.2. 设备(Devices)

设备(device)适配器的逻辑实例,通过它可以创建内部对象

设备通过 GPUDevice 暴露。

一个设备独占其上创建的所有内部对象:当该设备变为无效丢失销毁时),它本身和所有直接(如 createTexture())或间接(如 createView())创建的对象都会隐式变为不可用

设备具有如下不可变属性

[[adapter]],类型为 适配器,只读

创建该设备的适配器

[[features]],类型为 有序集合<GPUFeatureName>,只读

可在该设备上使用的特性,在创建时确定。即使底层适配器支持更多特性,也不能使用额外特性。

[[limits]],类型为支持的限制,只读

可在该设备上使用的限制,在创建时确定。即使底层适配器支持更高限制,也不能使用更高值(better)。

设备具有如下内容时间线属性

[[content device]],类型为 GPUDevice,只读

该设备关联的内容时间线 GPUDevice 接口实例。

要从适配器 adapterGPUDeviceDescriptor descriptor 创建新设备,请执行以下设备时间线步骤:
  1. featuresdescriptor.requiredFeatures 中值的有序集合

  2. 如果 features 包含 "texture-formats-tier2"

    1. 追加 "texture-formats-tier1"features

  3. 如果 features 包含 "texture-formats-tier1"

    1. 追加 "rg11b10ufloat-renderable"features

  4. 追加 "core-features-and-limits"features

  5. limits 为所有值均为默认值的支持的限制对象。

  6. 对于 descriptor.requiredLimits 中每个 (key, value):

    1. 如果 value 不为 undefinedvalue 优于 limits[key]:

      1. limits[key] = value

  7. device 为新设备对象。

  8. device.[[adapter]] = adapter

  9. device.[[features]] = features

  10. device.[[limits]] = limits

  11. 返回 device

每当用户代理需要撤销设备访问权限时,会在该设备的设备时间线上调用 丢失设备(device, "unknown"),该操作可能优先于当前队列中的其他操作。

如果某操作失败且副作用可能导致设备上的对象状态可见变化或内部实现/驱动状态损坏,应当丢失该设备以防止这些变化被观察到。

注: 非应用主动发起的设备丢失(通过 destroy())时,用户代理应无条件向开发者发出警告,即使 lost promise 已被处理。此类场景应极其罕见,并且该信号对开发者至关重要,因为大多数 WebGPU API 会尽量表现为“一切正常”以避免中断运行时流程:不会抛出校验错误,大多数 promise 正常 resolve 等。

丢失设备(device, reason),请执行以下设备时间线步骤:
  1. 使 device 无效

  2. device.[[content device]]内容时间线上执行:

    1. 用新的 GPUDeviceLostInfo resolve device.lost,其中 reason 设为 reasonmessage 设为实现自定义值。

      注: message 不应泄露不必要的用户/系统信息,且绝不应用于应用程序解析。

  3. 完成所有等待 device 变为丢失的未完成步骤。

注:丢失的设备不会再生成错误。参见 § 22 错误与调试

监听时间线事件 event设备 device,并由 timeline 上的 steps 处理:

则在 timeline 上执行 steps

3.6. 可选功能

WebGPU 适配器设备具备功能,这些功能描述了WebGPU在不同实现之间的差异, 通常是由于硬件或系统软件的限制。 一项功能可以是特性限制

用户代理不得透露超过32个可区分的配置或分组。

适配器的功能必须符合§ 4.2.1 适配器功能保证

仅支持的功能可以在requestDevice()中请求; 请求不支持的功能会导致失败。

设备的功能在"一个新的设备"中确定, 通过从适配器的默认值(无特性和默认的支持的限制)开始, 并根据在requestDevice()中请求的功能添加功能。 这些功能无论适配器的功能如何均会被强制执行。

这里是追踪向量。 有关隐私方面的考虑,请参阅§ 2.2.1 机器特定的功能和限制

3.6.1. 特性

特性是一组可选的 WebGPU 功能,并非所有实现都支持这些功能,通常是由于硬件或系统软件的限制所致。

所有特性都是可选的,但适配器会对其可用性做出一定保证 (参见§ 4.2.1 适配器功能保证)。

设备仅支持在创建时确定的那组特性(参见§ 3.6 可选功能)。 API 调用将根据这些特性(而非适配器的特性)进行校验:

只有当 GPUObjectBaseobject[[device]].[[features]] 包含 feature 时,GPUFeatureName feature 才被认为是 启用的

每个特性所启用的功能描述可参见特性索引

注意: 启用特性未必是理想选择,可能会影响性能。 因此,为了提升不同设备和实现间的可移植性,应用程序通常只应请求实际需要的特性。

3.6.2. 限制

每个限制都是对设备上 WebGPU 使用的数值限制。

注意: 设置“更好”的限制未必是理想选择,因为这样可能会对性能产生影响。 因此,为了提升不同设备和实现之间的可移植性,应用程序通常只有在确实需要时才请求比默认值更好的限制。

每个限制都有一个默认值。

适配器始终保证支持默认值或更好的 (参见§ 4.2.1 适配器功能保证)。

设备仅支持在创建时确定的那组限制(参见§ 3.6 可选功能)。 API 调用根据这些限制进行校验(而非适配器的限制), 不允许“更好”或更差。

对于任何给定的限制,一些值是更好的更好的限制值始终放宽校验,从而使更多程序变得有效。 对于每个限制类别,“更好”的定义如下。

不同的限制具有不同的限制类别

最大值

限制在传递给 API 的某些值上强制设置一个最大值。

更高的值是更好的

仅能设置为 ≥ 默认值 的值。 较低的值会被限制为默认值

对齐

限制在传递给 API 的某些值上强制设置一个最小对齐;即该值必须是限制的倍数。

较低的值是更好的

仅能设置为 ≤ 默认值 的2的幂次。 非2的幂次值是无效的。 更高的2的幂次值会被限制为默认值

支持的限制 对象具有 WebGPU 定义的每个限制的值:

限制名称 类型 限制类别 默认值
maxTextureDimension1D GPUSize32 最大值 8192
创建dimension "1d"纹理时, size.width 的最大允许值。
maxTextureDimension2D GPUSize32 最大值 8192
创建dimension "2d"纹理时, size.widthsize.height 的最大允许值。
maxTextureDimension3D GPUSize32 最大值 2048
创建dimension "3d"纹理时, size.widthsize.heightsize.depthOrArrayLayers 的最大允许值。
maxTextureArrayLayers GPUSize32 最大值 256
创建dimension "2d"纹理时, size.depthOrArrayLayers 的最大允许值。
maxBindGroups GPUSize32 最大值 4
创建GPUPipelineLayout时, bindGroupLayouts 中允许的GPUBindGroupLayouts的最大数量。
maxBindGroupsPlusVertexBuffers GPUSize32 最大值 24
同时使用的绑定组和顶点缓冲区槽位的最大数量,包括所有低于最大索引的空槽位。 在createRenderPipeline()绘制调用中验证。
maxBindingsPerBindGroup GPUSize32 最大值 1000
创建GPUBindGroupLayout时可用的绑定索引数量。

注意: 此限制具有规范性,但属于人为设定。 按默认绑定槽位限制,一个绑定组实际上无法使用1000个绑定, 但这允许GPUBindGroupLayoutEntry.binding 的值达到999。这一限制允许实现把绑定空间当作数组而不是稀疏映射结构,便于内存管理。

maxDynamicUniformBuffersPerPipelineLayout GPUSize32 最大值 8
在一个GPUPipelineLayout中, 所有为动态偏移的uniform buffer的GPUBindGroupLayoutEntry条目的最大数量。 详见绑定槽位限制说明
maxDynamicStorageBuffersPerPipelineLayout GPUSize32 最大值 4
在一个GPUPipelineLayout中, 所有为动态偏移的storage buffer的GPUBindGroupLayoutEntry条目的最大数量。 详见绑定槽位限制说明
maxSampledTexturesPerShaderStage GPUSize32 最大值 16
对于每个GPUShaderStage stage,在一个GPUPipelineLayout中, 所有采样纹理的GPUBindGroupLayoutEntry条目的最大数量。 详见绑定槽位限制说明
maxSamplersPerShaderStage GPUSize32 最大值 16
对于每个GPUShaderStage stage,在一个GPUPipelineLayout中, 所有采样器的GPUBindGroupLayoutEntry条目的最大数量。 详见绑定槽位限制说明
maxStorageBuffersPerShaderStage GPUSize32 最大值 8
对于每个GPUShaderStage stage,在一个GPUPipelineLayout中, 所有存储缓冲区的GPUBindGroupLayoutEntry条目的最大数量。 详见绑定槽位限制说明
maxStorageTexturesPerShaderStage GPUSize32 最大值 4
对于每个可能的GPUShaderStage stage, 在一个GPUPipelineLayout中, 所有存储纹理类型GPUBindGroupLayoutEntry的最大数量。 详见绑定槽位限制说明
maxUniformBuffersPerShaderStage GPUSize32 最大值 12
对于每个可能的GPUShaderStage stage, 在一个GPUPipelineLayout中, 所有uniform buffer类型GPUBindGroupLayoutEntry的最大数量。 详见绑定槽位限制说明
maxUniformBufferBindingSize GPUSize64 最大值 65536 字节
绑定类型为 GPUBindGroupLayoutEntry ,且entry.buffer?.type"uniform" 时, GPUBufferBinding.size 的最大值。
maxStorageBufferBindingSize GPUSize64 最大值 134217728 字节(128 MiB)
绑定类型为 GPUBindGroupLayoutEntry ,且entry.buffer?.type"storage""read-only-storage" 时, GPUBufferBinding.size 的最大值。
minUniformBufferOffsetAlignment GPUSize32 对齐 256 字节
绑定类型为 GPUBindGroupLayoutEntry ,且entry.buffer?.type"uniform" 时, GPUBufferBinding.offset 以及 setBindGroup() 传入的动态偏移量所需的对齐要求。
minStorageBufferOffsetAlignment GPUSize32 对齐 256 字节
绑定类型为 GPUBindGroupLayoutEntry ,且entry.buffer?.type"storage""read-only-storage" 时, GPUBufferBinding.offset 以及 setBindGroup() 传入的动态偏移量所需的对齐要求。
maxVertexBuffers GPUSize32 最大值 8
创建GPURenderPipeline时,允许的buffers的最大数量。
maxBufferSize GPUSize64 最大值 268435456 字节(256 MiB)
创建GPUBuffer时,size的最大数值。
maxVertexAttributes GPUSize32 最大值 16
创建GPURenderPipeline时,所有attributesbuffers中的总和的最大数量。
maxVertexBufferArrayStride GPUSize32 最大值 2048 字节
创建GPURenderPipeline时,arrayStride的最大允许值。
maxInterStageShaderVariables GPUSize32 最大值 16
阶段间通信(如顶点输出、片元输入)可用的输入或输出变量的最大数量。
maxColorAttachments GPUSize32 最大值 8
GPURenderPipelineDescriptor.fragment.targetsGPURenderPassDescriptor.colorAttachmentsGPURenderPassLayout.colorFormats 中允许的最大颜色附件数量。
maxColorAttachmentBytesPerSample GPUSize32 最大值 32
渲染管线输出数据中,跨所有颜色附件存储一个采样(像素或子像素)所需的最大字节数。
maxComputeWorkgroupStorageSize GPUSize32 最大值 16384 字节
一个计算阶段GPUShaderModule入口点可用的workgroup存储的最大字节数。
maxComputeInvocationsPerWorkgroup GPUSize32 最大值 256
一个计算阶段GPUShaderModule入口点的workgroup_size各维度乘积的最大值。
maxComputeWorkgroupSizeX GPUSize32 最大值 256
一个计算阶段GPUShaderModule入口点的workgroup_size X 维度的最大值。
maxComputeWorkgroupSizeY GPUSize32 最大值 256
一个计算阶段GPUShaderModule入口点的workgroup_size Y 维度的最大值。
maxComputeWorkgroupSizeZ GPUSize32 最大值 64
一个计算阶段GPUShaderModule入口点的workgroup_size Z 维度的最大值。
maxComputeWorkgroupsPerDimension GPUSize32 最大值 65535
dispatchWorkgroups(workgroupCountX, workgroupCountY, workgroupCountZ)的参数的最大值。
3.6.2.1. GPUSupportedLimits

GPUSupportedLimits 用于暴露适配器或设备的支持的限制。 参见 GPUAdapter.limitsGPUDevice.limits

[Exposed=(Window, Worker), SecureContext]
interface GPUSupportedLimits {
    readonly attribute unsigned long maxTextureDimension1D;
    readonly attribute unsigned long maxTextureDimension2D;
    readonly attribute unsigned long maxTextureDimension3D;
    readonly attribute unsigned long maxTextureArrayLayers;
    readonly attribute unsigned long maxBindGroups;
    readonly attribute unsigned long maxBindGroupsPlusVertexBuffers;
    readonly attribute unsigned long maxBindingsPerBindGroup;
    readonly attribute unsigned long maxDynamicUniformBuffersPerPipelineLayout;
    readonly attribute unsigned long maxDynamicStorageBuffersPerPipelineLayout;
    readonly attribute unsigned long maxSampledTexturesPerShaderStage;
    readonly attribute unsigned long maxSamplersPerShaderStage;
    readonly attribute unsigned long maxStorageBuffersPerShaderStage;
    readonly attribute unsigned long maxStorageTexturesPerShaderStage;
    readonly attribute unsigned long maxUniformBuffersPerShaderStage;
    readonly attribute unsigned long long maxUniformBufferBindingSize;
    readonly attribute unsigned long long maxStorageBufferBindingSize;
    readonly attribute unsigned long minUniformBufferOffsetAlignment;
    readonly attribute unsigned long minStorageBufferOffsetAlignment;
    readonly attribute unsigned long maxVertexBuffers;
    readonly attribute unsigned long long maxBufferSize;
    readonly attribute unsigned long maxVertexAttributes;
    readonly attribute unsigned long maxVertexBufferArrayStride;
    readonly attribute unsigned long maxInterStageShaderVariables;
    readonly attribute unsigned long maxColorAttachments;
    readonly attribute unsigned long maxColorAttachmentBytesPerSample;
    readonly attribute unsigned long maxComputeWorkgroupStorageSize;
    readonly attribute unsigned long maxComputeInvocationsPerWorkgroup;
    readonly attribute unsigned long maxComputeWorkgroupSizeX;
    readonly attribute unsigned long maxComputeWorkgroupSizeY;
    readonly attribute unsigned long maxComputeWorkgroupSizeZ;
    readonly attribute unsigned long maxComputeWorkgroupsPerDimension;
};
3.6.2.2. GPUSupportedFeatures

GPUSupportedFeatures 是一个 类似集合(setlike) 接口。它的 集合条目 是适配器或设备支持的 GPUFeatureName 值。 它只能包含 GPUFeatureName 枚举中的字符串。

[Exposed=(Window, Worker), SecureContext]
interface GPUSupportedFeatures {
    readonly setlike<DOMString>;
};
注意:
GPUSupportedFeatures集合条目 类型为 DOMString, 这样可以让用户代理优雅地处理后续规范修订中新增但用户代理尚未识别的有效 GPUFeatureName。 如果 集合条目 的类型是 GPUFeatureName,如下代码将抛出 TypeError, 而不是返回 false
检查对未知特性的支持:
if (adapter.features.has('unknown-feature')) {
    // 使用 unknown-feature
} else {
    console.warn('unknown-feature is not supported by this adapter.');
}
3.6.2.3. WGSLLanguageFeatures

WGSLLanguageFeaturesnavigator.gpu.wgslLanguageFeatures类似集合(setlike) 接口。 它的 集合条目 是该实现支持的 WGSL 语言扩展 的字符串名称(不论适配器或设备)。

[Exposed=(Window, Worker), SecureContext]
interface WGSLLanguageFeatures {
    readonly setlike<DOMString>;
};
3.6.2.4. GPUAdapterInfo

GPUAdapterInfo 用于暴露关于适配器的各种标识信息。

GPUAdapterInfo 的成员不保证有任何特定值;如果没有提供值,该属性将返回空字符串 ""。是否揭示这些值由用户代理自行决定,并且某些设备上可能所有值都为空。因此,应用必须能够处理任何可能的 GPUAdapterInfo 值,包括这些值缺失的情况。

适配器的 GPUAdapterInfo 可通过 GPUAdapter.infoGPUDevice.adapterInfo 获取。 这些信息是不可变的:对于某个适配器,每次访问同一个 GPUAdapterInfo 属性都会返回相同的值。

注意: 虽然 GPUAdapterInfo 属性一旦访问就不可变, 但实现可以在首次访问前延后决定每个属性的内容。

注意: 即便其他 GPUAdapter 实例代表同一物理适配器, 它们在 GPUAdapterInfo 中揭示的值也可能不同。 但除非有特殊事件提升了页面可访问的标识信息(本规范未定义此类事件),否则它们应当揭示相同的值。

There is a tracking vector here. 关于隐私考虑,请参见 § 2.2.6 适配器标识符

[Exposed=(Window, Worker), SecureContext]
interface GPUAdapterInfo {
    readonly attribute DOMString vendor;
    readonly attribute DOMString architecture;
    readonly attribute DOMString device;
    readonly attribute DOMString description;
    readonly attribute unsigned long subgroupMinSize;
    readonly attribute unsigned long subgroupMaxSize;
    readonly attribute boolean isFallbackAdapter;
};

GPUAdapterInfo 拥有如下属性:

vendor类型为 DOMString,只读

适配器的厂商名称(如有)。否则为空字符串。

architecture类型为 DOMString,只读

适配器所属 GPU 家族或类别的名称(如有)。否则为空字符串。

device类型为 DOMString,只读

适配器的厂商自定义标识符(如有)。否则为空字符串。

注意: 这是代表适配器类型的值。例如,可能是 PCI 设备ID。它不会像序列号一样唯一标识某块硬件。

description类型为 DOMString,只读

驱动报告的关于适配器的人类可读字符串描述(如有)。否则为空字符串。

注意: description 没有采用任何格式化,不建议尝试解析此值。根据 GPUAdapterInfo 改变行为的应用(如为已知驱动问题应用修正),应尽量依赖其他字段。

subgroupMinSize类型为 unsigned long,只读

如果支持 "subgroups" 特性,则为适配器支持的最小 子组大小

subgroupMaxSize类型为 unsigned long,只读

如果支持 "subgroups" 特性,则为适配器支持的最大 子组大小

isFallbackAdapter类型为 boolean,只读

适配器是否为回退适配器

要为指定的 adapter adapter 创建一个 新的适配器信息(new adapter info),请执行如下 内容时序 步骤:
  1. adapterInfo 为新的 GPUAdapterInfo

  2. 如果已知厂商,则将 adapterInfo.vendor 设为 adapter 的厂商名,并格式化为规范化标识符字符串。为保护隐私,用户代理也可以将 adapterInfo.vendor 设为空字符串,或一个合理近似的厂商名(同样为规范化标识符字符串)。

  3. 如果已知架构,则将 adapterInfo.architecture 设为代表 adapter 所属 GPU 家族或类别的规范化标识符字符串。为保护隐私,用户代理也可以设为空字符串,或合理近似的架构名(同样为规范化标识符字符串)。

  4. 如果已知设备,则将 adapterInfo.device 设为 adapter 的厂商自定义标识符,并格式化为规范化标识符字符串。为保护隐私,用户代理也可以设为空字符串,或合理近似的标识符(同样为规范化标识符字符串)。

  5. 如果已知描述,则将 adapterInfo.description 设为驱动报告的 adapter 描述。为保护隐私,用户代理也可以设为空字符串,或合理近似的描述。

  6. 如果支持 "subgroups" 特性,则将 subgroupMinSize 设为支持的最小子组大小;否则设为 4。

    注意: 为保护隐私,用户代理可以选择不支持某些特性,或为属性提供不会区分不同设备但依然可用的值(如对所有设备使用默认值 4)。

  7. 如果支持 "subgroups" 特性,则将 subgroupMaxSize 设为支持的最大子组大小;否则设为 128。

    注意: 为保护隐私,用户代理可以选择不支持某些特性,或为属性提供不会区分不同设备但依然可用的值(如对所有设备使用默认值 128)。

  8. adapterInfo.isFallbackAdapter 设为 adapter.[[fallback]]

  9. 返回 adapterInfo

规范化标识符字符串(normalized identifier string)指符合如下模式的字符串:

[a-z0-9]+(-[a-z0-9]+)*

a-z 0-9 -
合法规范化标识符字符串的示例包括:
  • gpu

  • 3d

  • 0x3b2f

  • next-gen

  • series-x20-ultra

3.7. 扩展文档

“扩展文档”是描述新功能的附加文档,这些功能是非规范性的,不属于 WebGPU/WGSL 规范的一部分。 它们描述了在这些规范基础上构建的功能,通常包含一个或多个新的 API 特性标志和/或 WGSL enable 指令,或与其他草案 Web 规范的交互。

WebGPU 实现不得暴露扩展功能;这样做属于规范违规。 新功能只有在被集成到 WebGPU 规范(本文档)和/或 WGSL 规范后,才成为 WebGPU 标准的一部分。

3.8. 源限制(Origin Restrictions)

WebGPU 允许访问存储在图片、视频和画布中的图像数据。 出于安全原因,对跨域媒体的使用施加了限制,因为着色器可以被用来间接推测已上传到 GPU 的纹理内容。

WebGPU 不允许上传 不是 origin-clean 的图片源。

这也意味着,使用 WebGPU 渲染的 canvas 的 origin-clean 标志永远不会被置为 false

关于为图片和视频元素发起 CORS 请求的更多信息,请参考:

3.9. 任务源(Task Sources)

3.9.1. WebGPU 任务源

WebGPU 定义了一个新的 任务源,称为 WebGPU 任务源。 它用于 uncapturederror 事件和 GPUDevice.lost

若要为 GPUDevice device 排队一个全局任务(queue a global task),并在 内容时序 上执行一系列步骤 steps
  1. WebGPU 任务源 上,为用于创建 device 的全局对象,按 steps 排队一个全局任务

3.9.2. 自动过期任务源

WebGPU 定义了一个新的 任务源,称为 自动过期任务源。 它用于自动、定时地销毁某些对象:

要用 GPUDevice device 和一系列步骤 steps内容时序排队一个自动过期任务
  1. 自动过期任务源 上,为用于创建 device 的全局对象,按 steps 排队一个全局任务

来自 自动过期任务源 的任务应当以高优先级处理;尤其是排入队列后,应当在用户自定义(JavaScript)任务之前执行。

注意:
这种行为更可预测,也能通过及早发现关于隐式生命周期的错误假设,帮助开发者编写更具移植性的应用程序。开发者仍然强烈建议在多个实现中进行测试。

实现说明: 以高优先级处理过期“任务”也可以通过在事件循环处理模型的某个固定点插入额外步骤来实现,而不一定非要运行实际的任务。

3.10. 色彩空间与编码

WebGPU 不提供色彩管理。WebGPU 内的所有值(如纹理元素)都是原始数值,不是经过色彩管理的色值。

WebGPU 确实与色彩管理的输出(通过 GPUCanvasConfiguration)和输入(通过 copyExternalImageToTexture()importExternalTexture())对接。因此,必须在 WebGPU 数值和外部色值之间进行色彩转换。每个接口点都会本地定义一种编码(色彩空间、传递函数和 alpha 预乘),用于解释 WebGPU 的数值。

WebGPU 允许 PredefinedColorSpace 枚举中的所有色彩空间。注意,每个色彩空间都定义了扩展范围(详见 CSS 相关定义),可以表示其空间外的颜色值(包括色度和明度)。

超出色域的预乘 RGBA 值指 R/G/B 其中任意一个通道的值大于 alpha 通道的值。例如,预乘 sRGB RGBA 值 [1.0, 0, 0, 0.5] 表示原始(未预乘)颜色 [2, 0, 0] 且 alpha 为 50%,在 CSS 中可写作 rgb(srgb 2 0 0 / 50%)。和所有 sRGB 色域外的颜色一样,这在扩展色彩空间中是有定义的点(alpha 为 0 时除外,此时没有颜色)。但若此类值输出到可见画布,结果未定义(见 GPUCanvasAlphaMode "premultiplied")。

3.10.1. 色彩空间转换

颜色在空间间转换时,需根据上述定义将其在一个空间中的表示转换为另一个空间中的表示。

如果源值少于4个 RGBA 通道,则缺失的绿/蓝/alpha 通道分别设为0, 0, 1,然后再做色彩空间/编码和 alpha 预乘转换。转换后,如果目标需要的通道数少于4,则忽略多余通道。

注意: 灰度图像通常在其色彩空间下表现为 RGB 值 (V, V, V) 或 RGBA 值 (V, V, V, A)

颜色在转换时不会被有损截断:若源色值本就在目标色彩空间的色域外,转换后会产生超出[0, 1]范围的值。例如,sRGB 目标下,如果源为 rgba16float,色彩空间更广(如 Display-P3),或为预乘且包含超出色域的预乘值,都可能出现上述情况。

同样,如果源值有高位深(如 16 位/分量 PNG)或扩展范围(如 float16 存储的 canvas),这些颜色会在转换过程中保留,且中间计算的精度不少于源。

3.10.2. 色彩空间转换省略

若源与目标的色彩空间/编码一致,则无需转换。通常,若某一步是恒等函数(无操作),实现应当出于性能考虑省略该步骤。

为获得最佳性能,应用应当设置色彩空间和编码选项,以最小化整个流程中所需的转换次数。 对于各种 GPUCopyExternalImageSourceInfo 图像源:

注意: 在依赖这些特性前,请检查浏览器的实现支持。

3.11. JavaScript 到 WGSL 的数值转换

WebGPU API 的多个部分(可覆盖管线 constants 和渲染通道清除值)会接收来自 WebIDL(doublefloat)的数值,并将其转换为 WGSL 值(booli32u32f32f16)。

将类型为 doublefloat 的 IDL 值 idlValue 转换为 WGSL 类型(to WGSL type) T,可能抛出 TypeError,请执行以下 设备时序 步骤:

注意:TypeError 只会在 设备时序 内产生,并不会抛到 JavaScript。

  1. 断言 idlValue 是有限值,因为它不是 unrestricted doubleunrestricted float

  2. vidlValue 转换为 ECMAScript 值 后得到的 ECMAScript Number。

  3. Tbool

    返回 WGSL bool 值,对应于 v 转换为 IDL boolean 类型后的结果。

    注意: 本算法在 ECMAScript 到 IDL doublefloat 的转换后调用。如果原始 ECMAScript 值是非数值、非布尔类型(如 []{}),则 WGSL bool 结果可能不同于直接转换为 IDL boolean 的结果。

    Ti32

    返回 WGSL i32 值,对应于 v 转为 [EnforceRange] long 的结果。

    Tu32

    返回 WGSL u32 值,对应于 v 转为 [EnforceRange] unsigned long 的结果。

    Tf32

    返回 WGSL f32 值,对应于 v 转为 float 的结果。

    Tf16
    1. wgslF32v 转为 float 的 WGSL f32 值。

    2. 返回 f16(wgslF32),即将 WGSL f32 值转换为 f16 的结果(见 WGSL 浮点数转换)。

    注意: 只要值在 f32 范围内,不会抛错,即使超出 f16 的范围。

若要将 GPUColor color 转换为纹理格式的 texel 值(to a texel value of texture format) format,可能抛出 TypeError,请执行以下 设备时序 步骤:

注意:TypeError 只会在 设备时序 内产生,并不会抛到 JavaScript。

  1. format 的各分量类型(断言全部相同)为:

    浮点类型或归一化类型

    Tf32

    有符号整型

    Ti32

    无符号整型

    Tu32

  2. wgslColor 为 WGSL vec4<T>,其 4 个分量为 color 的 RGBA 通道,每个都 转换为 WGSL 类型 T

  3. § 23.2.7 输出合并 的同样规则将 wgslColor 转换为 format,并返回结果。

    注意: 对于非整型类型,实际取值为实现定义。对于归一化类型,值会被限制在该类型允许的范围内。

注意: 换言之,写入的值就如同由 WGSL 着色器以 f32i32u32 类型的 vec4 输出。

4. Initialization

A GPU object is available in the Window and WorkerGlobalScope contexts through the Navigator and WorkerNavigator interfaces respectively and is exposed via navigator.gpu:

interface mixin NavigatorGPU {
    [SameObject, SecureContext] readonly attribute GPU gpu;
};
Navigator includes NavigatorGPU;
WorkerNavigator includes NavigatorGPU;

NavigatorGPU has the following attributes:

gpu, of type GPU, readonly

A global singleton providing top-level entry points like requestAdapter().

4.2. GPU

GPU is the entry point to WebGPU.

[Exposed=(Window, Worker), SecureContext]
interface GPU {
    Promise<GPUAdapter?> requestAdapter(optional GPURequestAdapterOptions options = {});
    GPUTextureFormat getPreferredCanvasFormat();
    [SameObject] readonly attribute WGSLLanguageFeatures wgslLanguageFeatures;
};

GPU has the following methods:

requestAdapter(options)

Requests an adapter from the user agent. The user agent chooses whether to return an adapter, and, if so, chooses according to the provided options.

Called on: GPU this.

Arguments:

Arguments for the GPU.requestAdapter(options) method.
Parameter Type Nullable Optional Description
options GPURequestAdapterOptions Criteria used to select the adapter.

Returns: Promise<GPUAdapter?>

Content timeline steps:

  1. Let contentTimeline be the current Content timeline.

  2. Let promise be a new promise.

  3. Issue the initialization steps on the Device timeline of this.

  4. Return promise.

Device timeline initialization steps:
  1. All of the requirements in the following steps must be met.

    1. options.featureLevel must be a feature level string.

    If they are met and the user agent chooses to return an adapter:

    1. Set adapter to an adapter chosen according to the rules in § 4.2.2 Adapter Selection and the criteria in options, adhering to § 4.2.1 Adapter Capability Guarantees. Initialize the properties of adapter according to their definitions:

      1. Set adapter.[[limits]] and adapter.[[features]] according to the supported capabilities of the adapter. adapter.[[features]] must contain "core-features-and-limits".

      2. If adapter meets the criteria of a fallback adapter set adapter.[[fallback]] to true. Otherwise, set it to false.

      3. Set adapter.[[xrCompatible]] to options.xrCompatible.

    Otherwise:

    1. Let adapter be null.

  2. Issue the subsequent steps on contentTimeline.

Content timeline steps:
  1. If adapter is not null:

    1. Resolve promise with a new GPUAdapter encapsulating adapter.

  2. Otherwise, Resolve promise with null.

getPreferredCanvasFormat()

Returns an optimal GPUTextureFormat for displaying 8-bit depth, standard dynamic range content on this system. Must only return "rgba8unorm" or "bgra8unorm".

The returned value can be passed as the format to configure() calls on a GPUCanvasContext to ensure the associated canvas is able to display its contents efficiently.

Note: Canvases which are not displayed to the screen may or may not benefit from using this format.

Called on: GPU this.

Returns: GPUTextureFormat

Content timeline steps:

  1. Return either "rgba8unorm" or "bgra8unorm", depending on which format is optimal for displaying WebGPU canvases on this system.

GPU has the following attributes:

wgslLanguageFeatures, of type WGSLLanguageFeatures, readonly

The names of supported WGSL language extensions. Supported language extensions are automatically enabled.

Adapters may expire at any time. Upon any change in the system’s state that could affect the result of any requestAdapter() call, the user agent should expire all previously-returned adapters. For example:

Note: User agents may choose to expire adapters often, even when there has been no system state change (e.g. seconds or minutes after the adapter was created). This can help obfuscate real system state changes, and make developers more aware that calling requestAdapter() again is always necessary before calling requestDevice(). If an application does encounter this situation, standard device-loss recovery handling should allow it to recover.

Requesting a GPUAdapter with no hints:
const gpuAdapter = await navigator.gpu.requestAdapter();

4.2.1. Adapter Capability Guarantees

Any GPUAdapter returned by requestAdapter() must provide the following guarantees:

4.2.2. Adapter Selection

GPURequestAdapterOptions provides hints to the user agent indicating what configuration is suitable for the application.

dictionary GPURequestAdapterOptions {
    DOMString featureLevel = "core";
    GPUPowerPreference powerPreference;
    boolean forceFallbackAdapter = false;
    boolean xrCompatible = false;
};
enum GPUPowerPreference {
    "low-power",
    "high-performance",
};

GPURequestAdapterOptions has the following members:

featureLevel, of type DOMString, defaulting to "core"

"Feature level" for the adapter request.

The allowed feature level string values are:

"core"

No effect.

"compatibility"

No effect.

Note: This value is reserved for future use as a way to opt into additional validation restrictions. Applications should not use this value at this time.

powerPreference, of type GPUPowerPreference

Optionally provides a hint indicating what class of adapter should be selected from the system’s available adapters.

The value of this hint may influence which adapter is chosen, but it must not influence whether an adapter is returned or not.

Note: The primary utility of this hint is to influence which GPU is used in a multi-GPU system. For instance, some laptops have a low-power integrated GPU and a high-performance discrete GPU. This hint may also affect the power configuration of the selected GPU to match the requested power preference.

Note: Depending on the exact hardware configuration, such as battery status and attached displays or removable GPUs, the user agent may select different adapters given the same power preference. Typically, given the same hardware configuration and state and powerPreference, the user agent is likely to select the same adapter.

It must be one of the following values:

undefined (or not present)

Provides no hint to the user agent.

"low-power"

Indicates a request to prioritize power savings over performance.

Note: Generally, content should use this if it is unlikely to be constrained by drawing performance; for example, if it renders only one frame per second, draws only relatively simple geometry with simple shaders, or uses a small HTML canvas element. Developers are encouraged to use this value if their content allows, since it may significantly improve battery life on portable devices.

"high-performance"

Indicates a request to prioritize performance over power consumption.

Note: By choosing this value, developers should be aware that, for devices created on the resulting adapter, user agents are more likely to force device loss, in order to save power by switching to a lower-power adapter. Developers are encouraged to only specify this value if they believe it is absolutely necessary, since it may significantly decrease battery life on portable devices.

forceFallbackAdapter, of type boolean, defaulting to false

When set to true indicates that only a fallback adapter may be returned. If the user agent does not support a fallback adapter, will cause requestAdapter() to resolve to null.

Note: requestAdapter() may still return a fallback adapter if forceFallbackAdapter is set to false and either no other appropriate adapter is available or the user agent chooses to return a fallback adapter. Developers that wish to prevent their applications from running on fallback adapters should check the info.isFallbackAdapter attribute prior to requesting a GPUDevice.

xrCompatible, of type boolean, defaulting to false

When set to true indicates that the best adapter for rendering to a WebXR session must be returned. If the user agent or system does not support WebXR sessions then adapter selection may ignore this value.

Note: If xrCompatible is not set to true when the adapter is requested, GPUDevices created from the adapter cannot be used to render for WebXR sessions.

Requesting a "high-performance" GPUAdapter:
const gpuAdapter = await navigator.gpu.requestAdapter({
    powerPreference: 'high-performance'
});

4.3. GPUAdapter

A GPUAdapter encapsulates an adapter, and describes its capabilities (features and limits).

To get a GPUAdapter, use requestAdapter().

[Exposed=(Window, Worker), SecureContext]
interface GPUAdapter {
    [SameObject] readonly attribute GPUSupportedFeatures features;
    [SameObject] readonly attribute GPUSupportedLimits limits;
    [SameObject] readonly attribute GPUAdapterInfo info;

    Promise<GPUDevice> requestDevice(optional GPUDeviceDescriptor descriptor = {});
};

GPUAdapter has the following immutable properties

features, of type GPUSupportedFeatures, readonly

The set of values in this.[[adapter]].[[features]].

limits, of type GPUSupportedLimits, readonly

The limits in this.[[adapter]].[[limits]].

info, of type GPUAdapterInfo, readonly

Information about the physical adapter underlying this GPUAdapter.

For a given GPUAdapter, the GPUAdapterInfo values exposed are constant over time.

The same object is returned each time. To create that object for the first time:

Called on: GPUAdapter this.

Returns: GPUAdapterInfo

Content timeline steps:

  1. Return a new adapter info for this.[[adapter]].

[[adapter]], of type adapter, readonly

The adapter to which this GPUAdapter refers.

GPUAdapter has the following methods:

requestDevice(descriptor)

Requests a device from the adapter.

This is a one-time action: if a device is returned successfully, the adapter becomes "consumed".

Called on: GPUAdapter this.

Arguments:

Arguments for the GPUAdapter.requestDevice(descriptor) method.
Parameter Type Nullable Optional Description
descriptor GPUDeviceDescriptor Description of the GPUDevice to request.

Returns: Promise<GPUDevice>

Content timeline steps:

  1. Let contentTimeline be the current Content timeline.

  2. Let promise be a new promise.

  3. Let adapter be this.[[adapter]].

  4. Issue the initialization steps to the Device timeline of this.

  5. Return promise.

Device timeline initialization steps:
  1. If any of the following requirements are unmet:

    Then issue the following steps on contentTimeline and return:

    Content timeline steps:
    1. Reject promise with a TypeError.

    Note: This is the same error that is produced if a feature name isn’t known by the browser at all (in its GPUFeatureName definition). This converges the behavior when the browser doesn’t support a feature with the behavior when a particular adapter doesn’t support a feature.

  2. All of the requirements in the following steps must be met.

    1. adapter.[[state]] must not be "consumed".

    2. For each [key, value] in descriptor.requiredLimits for which value is not undefined:

      1. key must be the name of a member of supported limits.

      2. value must be no better than adapter.[[limits]][key].

      3. If key’s class is alignment, value must be a power of 2 less than 232.

      Note: User agents should consider issuing developer-visible warnings when key is not recognized, even when value is undefined.

    If any are unmet, issue the following steps on contentTimeline and return:

    Content timeline steps:
    1. Reject promise with an OperationError.

  3. If adapter.[[state]] is "expired" or the user agent otherwise cannot fulfill the request:

    1. Let device be a new device.

    2. Lose the device(device, "unknown").

    3. Assert adapter.[[state]] is "expired".

      Note: User agents should consider issuing developer-visible warnings in most or all cases when this occurs. Applications should perform reinitialization logic starting with requestAdapter().

    Otherwise:

    1. Let device be a new device with the capabilities described by descriptor.

    2. Expire adapter.

  4. Issue the subsequent steps on contentTimeline.

Content timeline steps:
  1. Let gpuDevice be a new GPUDevice instance.

  2. Set gpuDevice.[[device]] to device.

  3. Set device.[[content device]] to gpuDevice.

  4. Set gpuDevice.label to descriptor.label.

  5. Resolve promise with gpuDevice.

    Note: If the device is already lost because the adapter could not fulfill the request, device.lost has already resolved before promise resolves.

Requesting a GPUDevice with default features and limits:
const gpuAdapter = await navigator.gpu.requestAdapter();
const gpuDevice = await gpuAdapter.requestDevice();

4.3.1. GPUDeviceDescriptor

GPUDeviceDescriptor describes a device request.

dictionary GPUDeviceDescriptor
         : GPUObjectDescriptorBase {
    sequence<GPUFeatureName> requiredFeatures = [];
    record<DOMString, (GPUSize64 or undefined)> requiredLimits = {};
    GPUQueueDescriptor defaultQueue = {};
};

GPUDeviceDescriptor has the following members:

requiredFeatures, of type sequence<GPUFeatureName>, defaulting to []

Specifies the features that are required by the device request. The request will fail if the adapter cannot provide these features.

Exactly the specified set of features, and no more or less, will be allowed in validation of API calls on the resulting device.

requiredLimits, of type record<DOMString, (GPUSize64 or undefined)>, defaulting to {}

Specifies the limits that are required by the device request. The request will fail if the adapter cannot provide these limits.

Each key with a non-undefined value must be the name of a member of supported limits.

API calls on the resulting device perform validation according to the exact limits of the device (not the adapter; see § 3.6.2 Limits).

defaultQueue, of type GPUQueueDescriptor, defaulting to {}

The descriptor for the default GPUQueue.

Requesting a GPUDevice with the "texture-compression-astc" feature if supported:
const gpuAdapter = await navigator.gpu.requestAdapter();

const requiredFeatures = [];
if (gpuAdapter.features.has('texture-compression-astc')) {
    requiredFeatures.push('texture-compression-astc')
}

const gpuDevice = await gpuAdapter.requestDevice({
    requiredFeatures
});
Requesting a GPUDevice with a higher maxColorAttachmentBytesPerSample limit:
const gpuAdapter = await navigator.gpu.requestAdapter();

if (gpuAdapter.limits.maxColorAttachmentBytesPerSample < 64) {
    // When the desired limit isn’t supported, take action to either fall back to a code
    // path that does not require the higher limit or notify the user that their device
    // does not meet minimum requirements.
}

// Request higher limit of max color attachments bytes per sample.
const gpuDevice = await gpuAdapter.requestDevice({
    requiredLimits: { maxColorAttachmentBytesPerSample: 64 },
});
4.3.1.1. GPUFeatureName

Each GPUFeatureName identifies a set of functionality which, if available, allows additional usages of WebGPU that would have otherwise been invalid.

enum GPUFeatureName {
    "core-features-and-limits",
    "depth-clip-control",
    "depth32float-stencil8",
    "texture-compression-bc",
    "texture-compression-bc-sliced-3d",
    "texture-compression-etc2",
    "texture-compression-astc",
    "texture-compression-astc-sliced-3d",
    "timestamp-query",
    "indirect-first-instance",
    "shader-f16",
    "rg11b10ufloat-renderable",
    "bgra8unorm-storage",
    "float32-filterable",
    "float32-blendable",
    "clip-distances",
    "dual-source-blending",
    "subgroups",
    "texture-formats-tier1",
    "texture-formats-tier2",
};

4.4. GPUDevice

A GPUDevice encapsulates a device and exposes the functionality of that device.

GPUDevice is the top-level interface through which WebGPU interfaces are created.

To get a GPUDevice, use requestDevice().

[Exposed=(Window, Worker), SecureContext]
interface GPUDevice : EventTarget {
    [SameObject] readonly attribute GPUSupportedFeatures features;
    [SameObject] readonly attribute GPUSupportedLimits limits;
    [SameObject] readonly attribute GPUAdapterInfo adapterInfo;

    [SameObject] readonly attribute GPUQueue queue;

    undefined destroy();

    GPUBuffer createBuffer(GPUBufferDescriptor descriptor);
    GPUTexture createTexture(GPUTextureDescriptor descriptor);
    GPUSampler createSampler(optional GPUSamplerDescriptor descriptor = {});
    GPUExternalTexture importExternalTexture(GPUExternalTextureDescriptor descriptor);

    GPUBindGroupLayout createBindGroupLayout(GPUBindGroupLayoutDescriptor descriptor);
    GPUPipelineLayout createPipelineLayout(GPUPipelineLayoutDescriptor descriptor);
    GPUBindGroup createBindGroup(GPUBindGroupDescriptor descriptor);

    GPUShaderModule createShaderModule(GPUShaderModuleDescriptor descriptor);
    GPUComputePipeline createComputePipeline(GPUComputePipelineDescriptor descriptor);
    GPURenderPipeline createRenderPipeline(GPURenderPipelineDescriptor descriptor);
    Promise<GPUComputePipeline> createComputePipelineAsync(GPUComputePipelineDescriptor descriptor);
    Promise<GPURenderPipeline> createRenderPipelineAsync(GPURenderPipelineDescriptor descriptor);

    GPUCommandEncoder createCommandEncoder(optional GPUCommandEncoderDescriptor descriptor = {});
    GPURenderBundleEncoder createRenderBundleEncoder(GPURenderBundleEncoderDescriptor descriptor);

    GPUQuerySet createQuerySet(GPUQuerySetDescriptor descriptor);
};
GPUDevice includes GPUObjectBase;

GPUDevice has the following immutable properties:

features, of type GPUSupportedFeatures, readonly

A set containing the GPUFeatureName values of the features supported by the device ([[device]].[[features]]).

limits, of type GPUSupportedLimits, readonly

The limits supported by the device ([[device]].[[limits]]).

queue, of type GPUQueue, readonly

The primary GPUQueue for this device.

adapterInfo, of type GPUAdapterInfo, readonly

Information about the physical adapter which created the device that this GPUDevice refers to.

For a given GPUDevice, the GPUAdapterInfo values exposed are constant over time.

The same object is returned each time. To create that object for the first time:

Called on: GPUDevice this.

Returns: GPUAdapterInfo

Content timeline steps:

  1. Return a new adapter info for this.[[device]].[[adapter]].

The [[device]] for a GPUDevice is the device that the GPUDevice refers to.

GPUDevice has the following methods:

destroy()

Destroys the device, preventing further operations on it. Outstanding asynchronous operations will fail.

Note: It is valid to destroy a device multiple times.

Called on: GPUDevice this.

Content timeline steps:

  1. unmap() all GPUBuffers from this device.

  2. Issue the subsequent steps on the Device timeline of this.

  1. Lose the device(this.[[device]], "destroyed").

Note: Since no further operations can be enqueued on this device, implementations can abort outstanding asynchronous operations immediately and free resource allocations, including mapped memory that was just unmapped.

A GPUDevice’s allowed buffer usages are:
A GPUDevice’s allowed texture usages are:

4.5. Example

A more robust example of requesting a GPUAdapter and GPUDevice with error handling:
let gpuDevice = null;

async function initializeWebGPU() {
    // Check to ensure the user agent supports WebGPU.
    if (!('gpu' in navigator)) {
        console.error("User agent doesn’t support WebGPU.");
        return false;
    }

    // Request an adapter.
    const gpuAdapter = await navigator.gpu.requestAdapter();

    // requestAdapter may resolve with null if no suitable adapters are found.
    if (!gpuAdapter) {
        console.error('No WebGPU adapters found.');
        return false;
    }

    // Request a device.
    // Note that the promise will reject if invalid options are passed to the optional
    // dictionary. To avoid the promise rejecting always check any features and limits
    // against the adapters features and limits prior to calling requestDevice().
    gpuDevice = await gpuAdapter.requestDevice();

    // requestDevice will never return null, but if a valid device request can’t be
    // fulfilled for some reason it may resolve to a device which has already been lost.
    // Additionally, devices can be lost at any time after creation for a variety of reasons
    // (ie: browser resource management, driver updates), so it’s a good idea to always
    // handle lost devices gracefully.
    gpuDevice.lost.then((info) => {
        console.error(`WebGPU device was lost: ${info.message}`);

        gpuDevice = null;

        // Many causes for lost devices are transient, so applications should try getting a
        // new device once a previous one has been lost unless the loss was caused by the
        // application intentionally destroying the device. Note that any WebGPU resources
        // created with the previous device (buffers, textures, etc) will need to be
        // re-created with the new one.
        if (info.reason != 'destroyed') {
            initializeWebGPU();
        }
    });

    onWebGPUInitialized();

    return true;
}

function onWebGPUInitialized() {
    // Begin creating WebGPU resources here...
}

initializeWebGPU();

5. Buffers

5.1. GPUBuffer

A GPUBuffer represents a block of memory that can be used in GPU operations. Data is stored in linear layout, meaning that each byte of the allocation can be addressed by its offset from the start of the GPUBuffer, subject to alignment restrictions depending on the operation. Some GPUBuffers can be mapped which makes the block of memory accessible via an ArrayBuffer called its mapping.

GPUBuffers are created via createBuffer(). Buffers may be mappedAtCreation.

[Exposed=(Window, Worker), SecureContext]
interface GPUBuffer {
    readonly attribute GPUSize64Out size;
    readonly attribute GPUFlagsConstant usage;

    readonly attribute GPUBufferMapState mapState;

    Promise<undefined> mapAsync(GPUMapModeFlags mode, optional GPUSize64 offset = 0, optional GPUSize64 size);
    ArrayBuffer getMappedRange(optional GPUSize64 offset = 0, optional GPUSize64 size);
    undefined unmap();

    undefined destroy();
};
GPUBuffer includes GPUObjectBase;

enum GPUBufferMapState {
    "unmapped",
    "pending",
    "mapped",
};

GPUBuffer has the following immutable properties:

size, of type GPUSize64Out, readonly

The length of the GPUBuffer allocation in bytes.

usage, of type GPUFlagsConstant, readonly

The allowed usages for this GPUBuffer.

GPUBuffer has the following content timeline properties:

mapState, of type GPUBufferMapState, readonly

The current GPUBufferMapState of the buffer:

"unmapped"

The buffer is not mapped for use by this.getMappedRange().

"pending"

A mapping of the buffer has been requested, but is pending. It may succeed, or fail validation in mapAsync().

"mapped"

The buffer is mapped and this.getMappedRange() may be used.

The getter steps are:

Content timeline steps:
  1. If this.[[mapping]] is not null, return "mapped".

  2. If this.[[pending_map]] is not null, return "pending".

  3. Return "unmapped".

[[pending_map]], of type Promise<void> or null, initially null

The Promise returned by the currently-pending mapAsync() call.

There is never more than one pending map, because mapAsync() will refuse immediately if a request is already in flight.

[[mapping]], of type active buffer mapping or null, initially null

Set if and only if the buffer is currently mapped for use by getMappedRange(). Null otherwise (even if there is a [[pending_map]]).

An active buffer mapping is a structure with the following fields:

data, of type Data Block

The mapping for this GPUBuffer. This data is accessed through ArrayBuffers which are views onto this data, returned by getMappedRange() and stored in views.

mode, of type GPUMapModeFlags

The GPUMapModeFlags of the map, as specified in the corresponding call to mapAsync() or createBuffer().

range, of type tuple [unsigned long long, unsigned long long]

The range of this GPUBuffer that is mapped.

views, of type list<ArrayBuffer>

The ArrayBuffers returned via getMappedRange() to the application. They are tracked so they can be detached when unmap() is called.

To initialize an active buffer mapping with mode mode and range range, run the following content timeline steps:
  1. Let size be range[1] - range[0].

  2. Let data be ? CreateByteDataBlock(size).

    NOTE:
    This may result in a RangeError being thrown. For consistency and predictability:
    • For any size at which new ArrayBuffer() would succeed at a given moment, this allocation should succeed at that moment.

    • For any size at which new ArrayBuffer() deterministically throws a RangeError, this allocation should as well.

  3. Return an active buffer mapping with:

Mapping and unmapping a buffer.
Failing to map a buffer.

GPUBuffer has the following device timeline properties:

[[internal state]]

The current internal state of the buffer:

"available"

The buffer may be used in queue operations (unless it is invalid).

"unavailable"

The buffer may not be used in queue operations due to being mapped.

"destroyed"

The buffer may not be used in any operations due to being destroy()ed.

5.1.1. GPUBufferDescriptor

dictionary GPUBufferDescriptor
         : GPUObjectDescriptorBase {
    required GPUSize64 size;
    required GPUBufferUsageFlags usage;
    boolean mappedAtCreation = false;
};

GPUBufferDescriptor has the following members:

size, of type GPUSize64

The size of the buffer in bytes.

usage, of type GPUBufferUsageFlags

The allowed usages for the buffer.

mappedAtCreation, of type boolean, defaulting to false

If true creates the buffer in an already mapped state, allowing getMappedRange() to be called immediately. It is valid to set mappedAtCreation to true even if usage does not contain MAP_READ or MAP_WRITE. This can be used to set the buffer’s initial data.

Guarantees that even if the buffer creation eventually fails, it will still appear as if the mapped range can be written/read to until it is unmapped.

5.1.2. Buffer Usages

typedef [EnforceRange] unsigned long GPUBufferUsageFlags;
[Exposed=(Window, Worker), SecureContext]
namespace GPUBufferUsage {
    const GPUFlagsConstant MAP_READ      = 0x0001;
    const GPUFlagsConstant MAP_WRITE     = 0x0002;
    const GPUFlagsConstant COPY_SRC      = 0x0004;
    const GPUFlagsConstant COPY_DST      = 0x0008;
    const GPUFlagsConstant INDEX         = 0x0010;
    const GPUFlagsConstant VERTEX        = 0x0020;
    const GPUFlagsConstant UNIFORM       = 0x0040;
    const GPUFlagsConstant STORAGE       = 0x0080;
    const GPUFlagsConstant INDIRECT      = 0x0100;
    const GPUFlagsConstant QUERY_RESOLVE = 0x0200;
};

The GPUBufferUsage flags determine how a GPUBuffer may be used after its creation:

MAP_READ

The buffer can be mapped for reading. (Example: calling mapAsync() with GPUMapMode.READ)

May only be combined with COPY_DST.

MAP_WRITE

The buffer can be mapped for writing. (Example: calling mapAsync() with GPUMapMode.WRITE)

May only be combined with COPY_SRC.

COPY_SRC

The buffer can be used as the source of a copy operation. (Examples: as the source argument of a copyBufferToBuffer() or copyBufferToTexture() call.)

COPY_DST

The buffer can be used as the destination of a copy or write operation. (Examples: as the destination argument of a copyBufferToBuffer() or copyTextureToBuffer() call, or as the target of a writeBuffer() call.)

INDEX

The buffer can be used as an index buffer. (Example: passed to setIndexBuffer().)

VERTEX

The buffer can be used as a vertex buffer. (Example: passed to setVertexBuffer().)

UNIFORM

The buffer can be used as a uniform buffer. (Example: as a bind group entry for a GPUBufferBindingLayout with a buffer.type of "uniform".)

STORAGE

The buffer can be used as a storage buffer. (Example: as a bind group entry for a GPUBufferBindingLayout with a buffer.type of "storage" or "read-only-storage".)

INDIRECT

The buffer can be used as to store indirect command arguments. (Examples: as the indirectBuffer argument of a drawIndirect() or dispatchWorkgroupsIndirect() call.)

QUERY_RESOLVE

The buffer can be used to capture query results. (Example: as the destination argument of a resolveQuerySet() call.)

5.1.3. Buffer Creation

createBuffer(descriptor)

Creates a GPUBuffer.

Called on: GPUDevice this.

Arguments:

Arguments for the GPUDevice.createBuffer(descriptor) method.
Parameter Type Nullable Optional Description
descriptor GPUBufferDescriptor Description of the GPUBuffer to create.

Returns: GPUBuffer

Content timeline steps:

  1. Let b be ! create a new WebGPU object(this, GPUBuffer, descriptor).

  2. Set b.size to descriptor.size.

  3. Set b.usage to descriptor.usage.

  4. If descriptor.mappedAtCreation is true:

    1. If descriptor.size is not a multiple of 4, throw a RangeError.

    2. Set b.[[mapping]] to ? initialize an active buffer mapping with mode WRITE and range [0, descriptor.size].

  5. Issue the initialization steps on the Device timeline of this.

  6. Return b.

Device timeline initialization steps:
  1. If any of the following requirements are unmet, generate a validation error, invalidate b and return.

Note: If buffer creation fails, and descriptor.mappedAtCreation is false, any calls to mapAsync() will reject, so any resources allocated to enable mapping can and may be discarded or recycled.

  1. If descriptor.mappedAtCreation is true:

    1. Set b.[[internal state]] to "unavailable".

    Else:

    1. Set b.[[internal state]] to "available".

  2. Create a device allocation for b where each byte is zero.

    If the allocation fails without side-effects, generate an out-of-memory error, invalidate b, and return.

Creating a 128 byte uniform buffer that can be written into:
const buffer = gpuDevice.createBuffer({
    size: 128,
    usage: GPUBufferUsage.UNIFORM | GPUBufferUsage.COPY_DST
});

5.1.4. Buffer Destruction

An application that no longer requires a GPUBuffer can choose to lose access to it before garbage collection by calling destroy(). Destroying a buffer also unmaps it, freeing any memory allocated for the mapping.

Note: This allows the user agent to reclaim the GPU memory associated with the GPUBuffer once all previously submitted operations using it are complete.

GPUBuffer has the following methods:

destroy()

Destroys the GPUBuffer.

Note: It is valid to destroy a buffer multiple times.

Called on: GPUBuffer this.

Returns: undefined

Content timeline steps:

  1. Call this.unmap().

  2. Issue the subsequent steps on the Device timeline of this.[[device]].

Device timeline steps:
  1. Set this.[[internal state]] to "destroyed".

Note: Since no further operations can be enqueued using this buffer, implementations can free resource allocations, including mapped memory that was just unmapped.

5.2. Buffer Mapping

An application can request to map a GPUBuffer so that they can access its content via ArrayBuffers that represent part of the GPUBuffer’s allocations. Mapping a GPUBuffer is requested asynchronously with mapAsync() so that the user agent can ensure the GPU finished using the GPUBuffer before the application can access its content. A mapped GPUBuffer cannot be used by the GPU and must be unmapped using unmap() before work using it can be submitted to the Queue timeline.

Once the GPUBuffer is mapped, the application can synchronously ask for access to ranges of its content with getMappedRange(). The returned ArrayBuffer can only be detached by unmap() (directly, or via GPUBuffer.destroy() or GPUDevice.destroy()), and cannot be transferred. A TypeError is thrown by any other operation that attempts to do so.

typedef [EnforceRange] unsigned long GPUMapModeFlags;
[Exposed=(Window, Worker), SecureContext]
namespace GPUMapMode {
    const GPUFlagsConstant READ  = 0x0001;
    const GPUFlagsConstant WRITE = 0x0002;
};

The GPUMapMode flags determine how a GPUBuffer is mapped when calling mapAsync():

READ

Only valid with buffers created with the MAP_READ usage.

Once the buffer is mapped, calls to getMappedRange() will return an ArrayBuffer containing the buffer’s current values. Changes to the returned ArrayBuffer will be discarded after unmap() is called.

WRITE

Only valid with buffers created with the MAP_WRITE usage.

Once the buffer is mapped, calls to getMappedRange() will return an ArrayBuffer containing the buffer’s current values. Changes to the returned ArrayBuffer will be stored in the GPUBuffer after unmap() is called.

Note: Since the MAP_WRITE buffer usage may only be combined with the COPY_SRC buffer usage, mapping for writing can never return values produced by the GPU, and the returned ArrayBuffer will only ever contain the default initialized data (zeros) or data written by the webpage during a previous mapping.

GPUBuffer has the following methods:

mapAsync(mode, offset, size)

Maps the given range of the GPUBuffer and resolves the returned Promise when the GPUBuffer’s content is ready to be accessed with getMappedRange().

The resolution of the returned Promise only indicates that the buffer has been mapped. It does not guarantee the completion of any other operations visible to the content timeline, and in particular does not imply that any other Promise returned from onSubmittedWorkDone() or mapAsync() on other GPUBuffers have resolved.

The resolution of the Promise returned from onSubmittedWorkDone() does imply the completion of mapAsync() calls made prior to that call, on GPUBuffers last used exclusively on that queue.

Called on: GPUBuffer this.

Arguments:

Arguments for the GPUBuffer.mapAsync(mode, offset, size) method.
Parameter Type Nullable Optional Description
mode GPUMapModeFlags Whether the buffer should be mapped for reading or writing.
offset GPUSize64 Offset in bytes into the buffer to the start of the range to map.
size GPUSize64 Size in bytes of the range to map.

Returns: Promise<undefined>

Content timeline steps:

  1. Let contentTimeline be the current Content timeline.

  2. If this.mapState is not "unmapped":

    1. Issue the early-reject steps on the Device timeline of this.[[device]].

    2. Return a promise rejected with OperationError.

  3. Let p be a new Promise.

  4. Set this.[[pending_map]] to p.

  5. Issue the validation steps on the Device timeline of this.[[device]].

  6. Return p.

Device timeline early-reject steps:
  1. Generate a validation error.

  2. Return.

Device timeline validation steps:
  1. If size is undefined:

    1. Let rangeSize be max(0, this.size - offset).

    Otherwise:

    1. Let rangeSize be size.

  2. If any of the following conditions are unsatisfied:

    1. Set deviceLost to true.

    2. Issue the map failure steps on contentTimeline.

    3. Return.

  3. If any of the following conditions are unsatisfied:

    Then:

    1. Set deviceLost to false.

    2. Issue the map failure steps on contentTimeline.

    3. Generate a validation error.

    4. Return.

  4. Set this.[[internal state]] to "unavailable".

    Note: Since the buffer is mapped, its contents cannot change between this step and unmap().

  5. When either of the following events occur (whichever comes first), or if either has already occurred:

    • The device timeline becomes informed of the completion of an unspecified queue timeline point:

      • after the completion of currently-enqueued operations that use this

      • and no later than the completion of all currently-enqueued operations (regardless of whether they use this).

    • this.[[device]] becomes lost.

    Then issue the subsequent steps on the device timeline of this.[[device]].

Device timeline steps:
  1. Set deviceLost to true if this.[[device]] is lost, and false otherwise.

    Note: The device could have been lost between the previous block of steps and this one.

  2. If deviceLost:

    1. Issue the map failure steps on contentTimeline.

    Otherwise:

    1. Let internalStateAtCompletion be this.[[internal state]].

      Note: If, and only if, at this point the buffer has become "available" again due to an unmap() call, then [[pending_map]] != p below, so mapping will not succeed in the steps below.

    2. Let dataForMappedRegion be the contents of this starting at offset offset, for rangeSize bytes.

    3. Issue the map success steps on the contentTimeline.

Content timeline map success steps:
  1. If this.[[pending_map]] != p:

    Note: The map has been cancelled by unmap().

    1. Assert p is rejected.

    2. Return.

  2. Assert p is pending.

  3. Assert internalStateAtCompletion is "unavailable".

  4. Let mapping be initialize an active buffer mapping with mode mode and range [offset, offset + rangeSize].

    If this allocation fails:

    1. Set this.[[pending_map]] to null, and reject p with a RangeError.

    2. Return.

  5. Set the content of mapping.data to dataForMappedRegion.

  6. Set this.[[mapping]] to mapping.

  7. Set this.[[pending_map]] to null, and resolve p.

Content timeline map failure steps:
  1. If this.[[pending_map]] != p:

    Note: The map has been cancelled by unmap().

    1. Assert p is already rejected.

    2. Return.

  2. Assert p is still pending.

  3. Set this.[[pending_map]] to null.

  4. If deviceLost:

    1. Reject p with an AbortError.

      Note: This is the same error type produced by cancelling the map using unmap().

    Otherwise:

    1. Reject p with an OperationError.

getMappedRange(offset, size)

Returns an ArrayBuffer with the contents of the GPUBuffer in the given mapped range.

Called on: GPUBuffer this.

Arguments:

Arguments for the GPUBuffer.getMappedRange(offset, size) method.
Parameter Type Nullable Optional Description
offset GPUSize64 Offset in bytes into the buffer to return buffer contents from.
size GPUSize64 Size in bytes of the ArrayBuffer to return.

Returns: ArrayBuffer

Content timeline steps:

  1. If size is missing:

    1. Let rangeSize be max(0, this.size - offset).

    Otherwise, let rangeSize be size.

  2. If any of the following conditions are unsatisfied, throw an OperationError and return.

    Note: It is always valid to get mapped ranges of a GPUBuffer that is mappedAtCreation, even if it is invalid, because the Content timeline might not know it is invalid.

  3. Let data be this.[[mapping]].data.

  4. Let view be ! create an ArrayBuffer of size rangeSize, but with its pointer mutably referencing the content of data at offset (offset - [[mapping]].range[0]).

    Note: A RangeError may not be thrown here, because the data has already been allocated during mapAsync() or createBuffer().

  5. Set view.[[ArrayBufferDetachKey]] to "WebGPUBufferMapping".

    Note: This causes a TypeError to be thrown if an attempt is made to DetachArrayBuffer, except by unmap().

  6. Append view to this.[[mapping]].views.

  7. Return view.

Note: User agents should consider issuing a developer-visible warning if getMappedRange() succeeds without having checked the status of the map, by waiting for mapAsync() to succeed, querying a mapState of "mapped", or waiting for a later onSubmittedWorkDone() call to succeed.

unmap()

Unmaps the mapped range of the GPUBuffer and makes its contents available for use by the GPU again.

Called on: GPUBuffer this.

Returns: undefined

Content timeline steps:

  1. If this.[[pending_map]] is not null:

    1. Reject this.[[pending_map]] with an AbortError.

    2. Set this.[[pending_map]] to null.

  2. If this.[[mapping]] is null:

    1. Return.

  3. For each ArrayBuffer ab in this.[[mapping]].views:

    1. Perform DetachArrayBuffer(ab, "WebGPUBufferMapping").

  4. Let bufferUpdate be null.

  5. If this.[[mapping]].mode contains WRITE:

    1. Set bufferUpdate to { data: this.[[mapping]].data, offset: this.[[mapping]].range[0] }.

    Note: When a buffer is mapped without the WRITE mode, then unmapped, any local modifications done by the application to the mapped ranges ArrayBuffer are discarded and will not affect the content of later mappings.

  6. Set this.[[mapping]] to null.

  7. Issue the subsequent steps on the Device timeline of this.[[device]].

Device timeline steps:
  1. If any of the following conditions are unsatisfied, return.

  2. Assert this.[[internal state]] is "unavailable".

  3. If bufferUpdate is not null:

    1. Issue the following steps on the Queue timeline of this.[[device]].queue:

      Queue timeline steps:
      1. Update the contents of this at offset bufferUpdate.offset with the data bufferUpdate.data.

  4. Set this.[[internal state]] to "available".

6. Textures and Texture Views

6.1. GPUTexture

A texture is made up of 1d, 2d, or 3d arrays of data which can contain multiple values per-element to represent things like colors. Textures can be read and written in many ways, depending on the GPUTextureUsage they are created with. For example, textures can be sampled, read, and written from render and compute pipeline shaders, and they can be written by render pass outputs. Internally, textures are often stored in GPU memory with a layout optimized for multidimensional access rather than linear access.

One texture consists of one or more texture subresources, each uniquely identified by a mipmap level and, for 2d textures only, array layer and aspect.

A texture subresource is a subresource: each can be used in different internal usages within a single usage scope.

Each subresource in a mipmap level is approximately half the size, in each spatial dimension, of the corresponding resource in the lesser level (see logical miplevel-specific texture extent). The subresource in level 0 has the dimensions of the texture itself. Smaller levels are typically used to store lower resolution versions of the same image. GPUSampler and WGSL provide facilities for selecting and interpolating between levels of detail, explicitly or automatically.

A "2d" texture may be an array of array layers. Each subresource in a layer is the same size as the corresponding resources in other layers. For non-2d textures, all subresources have an array layer index of 0.

Each subresource has an aspect. Color textures have just one aspect: color. Depth-or-stencil format textures may have multiple aspects: a depth aspect, a stencil aspect, or both, and may be used in special ways, such as in depthStencilAttachment and in "depth" bindings.

A "3d" texture may have multiple slices, each being the two-dimensional image at a particular z value in the texture. Slices are not separate subresources.

[Exposed=(Window, Worker), SecureContext]
interface GPUTexture {
    GPUTextureView createView(optional GPUTextureViewDescriptor descriptor = {});

    undefined destroy();

    readonly attribute GPUIntegerCoordinateOut width;
    readonly attribute GPUIntegerCoordinateOut height;
    readonly attribute GPUIntegerCoordinateOut depthOrArrayLayers;
    readonly attribute GPUIntegerCoordinateOut mipLevelCount;
    readonly attribute GPUSize32Out sampleCount;
    readonly attribute GPUTextureDimension dimension;
    readonly attribute GPUTextureFormat format;
    readonly attribute GPUFlagsConstant usage;
};
GPUTexture includes GPUObjectBase;

GPUTexture has the following immutable properties:

width, of type GPUIntegerCoordinateOut, readonly

The width of this GPUTexture.

height, of type GPUIntegerCoordinateOut, readonly

The height of this GPUTexture.

depthOrArrayLayers, of type GPUIntegerCoordinateOut, readonly

The depth or layer count of this GPUTexture.

mipLevelCount, of type GPUIntegerCoordinateOut, readonly

The number of mip levels of this GPUTexture.

sampleCount, of type GPUSize32Out, readonly

The number of sample count of this GPUTexture.

dimension, of type GPUTextureDimension, readonly

The dimension of the set of texel for each of this GPUTexture’s subresources.

format, of type GPUTextureFormat, readonly

The format of this GPUTexture.

usage, of type GPUFlagsConstant, readonly

The allowed usages for this GPUTexture.

[[viewFormats]], of type sequence<GPUTextureFormat>

The set of GPUTextureFormats that can be used as the GPUTextureViewDescriptor.format when creating views on this GPUTexture.

GPUTexture has the following device timeline properties:

[[destroyed]], of type boolean, initially false

If the texture is destroyed, it can no longer be used in any operation, and its underlying memory can be freed.

compute render extent(baseSize, mipLevel)

Arguments:

Returns: GPUExtent3DDict

Device timeline steps:

  1. Let extent be a new GPUExtent3DDict object.

  2. Set extent.width to max(1, baseSize.widthmipLevel).

  3. Set extent.height to max(1, baseSize.heightmipLevel).

  4. Set extent.depthOrArrayLayers to 1.

  5. Return extent.

The logical miplevel-specific texture extent of a texture is the size of the texture in texels at a specific miplevel. It is calculated by this procedure:

Logical miplevel-specific texture extent(descriptor, mipLevel)

Arguments:

Returns: GPUExtent3DDict

  1. Let extent be a new GPUExtent3DDict object.

  2. If descriptor.dimension is:

    "1d"
    "2d"
    "3d"
  3. Return extent.

The physical miplevel-specific texture extent of a texture is the size of the texture in texels at a specific miplevel that includes the possible extra padding to form complete texel blocks in the texture. It is calculated by this procedure:

Physical miplevel-specific texture extent(descriptor, mipLevel)

Arguments:

Returns: GPUExtent3DDict

  1. Let extent be a new GPUExtent3DDict object.

  2. Let logicalExtent be logical miplevel-specific texture extent(descriptor, mipLevel).

  3. If descriptor.dimension is:

    "1d"
    "2d"
    "3d"
  4. Return extent.

6.1.1. GPUTextureDescriptor

dictionary GPUTextureDescriptor
         : GPUObjectDescriptorBase {
    required GPUExtent3D size;
    GPUIntegerCoordinate mipLevelCount = 1;
    GPUSize32 sampleCount = 1;
    GPUTextureDimension dimension = "2d";
    required GPUTextureFormat format;
    required GPUTextureUsageFlags usage;
    sequence<GPUTextureFormat> viewFormats = [];
};

GPUTextureDescriptor has the following members:

size, of type GPUExtent3D

The width, height, and depth or layer count of the texture.

mipLevelCount, of type GPUIntegerCoordinate, defaulting to 1

The number of mip levels the texture will contain.

sampleCount, of type GPUSize32, defaulting to 1

The sample count of the texture. A sampleCount > 1 indicates a multisampled texture.

dimension, of type GPUTextureDimension, defaulting to "2d"

Whether the texture is one-dimensional, an array of two-dimensional layers, or three-dimensional.

format, of type GPUTextureFormat

The format of the texture.

usage, of type GPUTextureUsageFlags

The allowed usages for the texture.

viewFormats, of type sequence<GPUTextureFormat>, defaulting to []

Specifies what view format values will be allowed when calling createView() on this texture (in addition to the texture’s actual format).

NOTE:
Adding a format to this list may have a significant performance impact, so it is best to avoid adding formats unnecessarily.

The actual performance impact is highly dependent on the target system; developers must test various systems to find out the impact on their particular application. For example, on some systems any texture with a format or viewFormats entry including "rgba8unorm-srgb" will perform less optimally than a "rgba8unorm" texture which does not. Similar caveats exist for other formats and pairs of formats on other systems.

Formats in this list must be texture view format compatible with the texture format.

Two GPUTextureFormats format and viewFormat are texture view format compatible if:
  • format equals viewFormat, or

  • format and viewFormat differ only in whether they are srgb formats (have the -srgb suffix).

enum GPUTextureDimension {
    "1d",
    "2d",
    "3d",
};
"1d"

Specifies a texture that has one dimension, width. "1d" textures cannot have mipmaps, be multisampled, use compressed or depth/stencil formats, or be used as a render target.

"2d"

Specifies a texture that has a width and height, and may have layers.

"3d"

Specifies a texture that has a width, height, and depth. "3d" textures cannot be multisampled, and their format must support 3d textures (all plain color formats and some packed/compressed formats).

6.1.2. Texture Usages

typedef [EnforceRange] unsigned long GPUTextureUsageFlags;
[Exposed=(Window, Worker), SecureContext]
namespace GPUTextureUsage {
    const GPUFlagsConstant COPY_SRC          = 0x01;
    const GPUFlagsConstant COPY_DST          = 0x02;
    const GPUFlagsConstant TEXTURE_BINDING   = 0x04;
    const GPUFlagsConstant STORAGE_BINDING   = 0x08;
    const GPUFlagsConstant RENDER_ATTACHMENT = 0x10;
};

The GPUTextureUsage flags determine how a GPUTexture may be used after its creation:

COPY_SRC

The texture can be used as the source of a copy operation. (Examples: as the source argument of a copyTextureToTexture() or copyTextureToBuffer() call.)

COPY_DST

The texture can be used as the destination of a copy or write operation. (Examples: as the destination argument of a copyTextureToTexture() or copyBufferToTexture() call, or as the target of a writeTexture() call.)

TEXTURE_BINDING

The texture can be bound for use as a sampled texture in a shader (Example: as a bind group entry for a GPUTextureBindingLayout.)

STORAGE_BINDING

The texture can be bound for use as a storage texture in a shader (Example: as a bind group entry for a GPUStorageTextureBindingLayout.)

RENDER_ATTACHMENT

The texture can be used as a color or depth/stencil attachment in a render pass. (Example: as a GPURenderPassColorAttachment.view or GPURenderPassDepthStencilAttachment.view.)

maximum mipLevel count(dimension, size)

Arguments:

  1. Calculate the max dimension value m:

  2. Return floor(log2(m)) + 1.

6.1.3. Texture Creation

createTexture(descriptor)

Creates a GPUTexture.

Called on: GPUDevice this.

Arguments:

Arguments for the GPUDevice.createTexture(descriptor) method.
Parameter Type Nullable Optional Description
descriptor GPUTextureDescriptor Description of the GPUTexture to create.

Returns: GPUTexture

Content timeline steps:

  1. ? validate GPUExtent3D shape(descriptor.size).

  2. ? Validate texture format required features of descriptor.format with this.[[device]].

  3. ? Validate texture format required features of each element of descriptor.viewFormats with this.[[device]].

  4. Let t be ! create a new WebGPU object(this, GPUTexture, descriptor).

  5. Set t.width to descriptor.size.width.

  6. Set t.height to descriptor.size.height.

  7. Set t.depthOrArrayLayers to descriptor.size.depthOrArrayLayers.

  8. Set t.mipLevelCount to descriptor.mipLevelCount.

  9. Set t.sampleCount to descriptor.sampleCount.

  10. Set t.dimension to descriptor.dimension.

  11. Set t.format to descriptor.format.

  12. Set t.usage to descriptor.usage.

  13. Issue the initialization steps on the Device timeline of this.

  14. Return t.

Device timeline initialization steps:
  1. If any of the following conditions are unsatisfied generate a validation error, invalidate t and return.

  2. Set t.[[viewFormats]] to descriptor.viewFormats.

  3. Create a device allocation for t where each block has an equivalent texel representation to a block with a bit representation of zero.

    If the allocation fails without side-effects, generate an out-of-memory error, invalidate t, and return.

validating GPUTextureDescriptor(this, descriptor):

Arguments:

Device timeline steps:

  1. Let limits be this.[[limits]].

  2. Return true if all of the following requirements are met, and false otherwise:

Creating a 16x16, RGBA, 2D texture with one array layer and one mip level:
const texture = gpuDevice.createTexture({
    size: { width: 16, height: 16 },
    format: 'rgba8unorm',
    usage: GPUTextureUsage.TEXTURE_BINDING,
});

6.1.4. Texture Destruction

An application that no longer requires a GPUTexture can choose to lose access to it before garbage collection by calling destroy().

Note: This allows the user agent to reclaim the GPU memory associated with the GPUTexture once all previously submitted operations using it are complete.

GPUTexture has the following methods:

destroy()

Destroys the GPUTexture.

Called on: GPUTexture this.

Returns: undefined

Content timeline steps:

  1. Issue the subsequent steps on the device timeline.

Device timeline steps:
  1. Set this.[[destroyed]] to true.

6.2. GPUTextureView

A GPUTextureView is a view onto some subset of the texture subresources defined by a particular GPUTexture.

[Exposed=(Window, Worker), SecureContext]
interface GPUTextureView {
};
GPUTextureView includes GPUObjectBase;

GPUTextureView has the following immutable properties:

[[texture]], readonly

The GPUTexture into which this is a view.

[[descriptor]], readonly

The GPUTextureViewDescriptor describing this texture view.

All optional fields of GPUTextureViewDescriptor are defined.

[[renderExtent]], readonly

For renderable views, this is the effective GPUExtent3DDict for rendering.

Note: this extent depends on the baseMipLevel.

The set of subresources of a texture view view, with [[descriptor]] desc, is the subset of the subresources of view.[[texture]] for which each subresource s satisfies the following:

Two GPUTextureView objects are texture-view-aliasing if and only if their sets of subresources intersect.

6.2.1. Texture View Creation

dictionary GPUTextureViewDescriptor
         : GPUObjectDescriptorBase {
    GPUTextureFormat format;
    GPUTextureViewDimension dimension;
    GPUTextureUsageFlags usage = 0;
    GPUTextureAspect aspect = "all";
    GPUIntegerCoordinate baseMipLevel = 0;
    GPUIntegerCoordinate mipLevelCount;
    GPUIntegerCoordinate baseArrayLayer = 0;
    GPUIntegerCoordinate arrayLayerCount;
};

GPUTextureViewDescriptor has the following members:

format, of type GPUTextureFormat

The format of the texture view. Must be either the format of the texture or one of the viewFormats specified during its creation.

dimension, of type GPUTextureViewDimension

The dimension to view the texture as.

usage, of type GPUTextureUsageFlags, defaulting to 0

The allowed usage(s) for the texture view. Must be a subset of the usage flags of the texture. If 0, defaults to the full set of usage flags of the texture.

Note: If the view’s format doesn’t support all of the texture’s usages, the default will fail, and the view’s usage must be specified explicitly.

aspect, of type GPUTextureAspect, defaulting to "all"

Which aspect(s) of the texture are accessible to the texture view.

baseMipLevel, of type GPUIntegerCoordinate, defaulting to 0

The first (most detailed) mipmap level accessible to the texture view.

mipLevelCount, of type GPUIntegerCoordinate

How many mipmap levels, starting with baseMipLevel, are accessible to the texture view.

baseArrayLayer, of type GPUIntegerCoordinate, defaulting to 0

The index of the first array layer accessible to the texture view.

arrayLayerCount, of type GPUIntegerCoordinate

How many array layers, starting with baseArrayLayer, are accessible to the texture view.

enum GPUTextureViewDimension {
    "1d",
    "2d",
    "2d-array",
    "cube",
    "cube-array",
    "3d",
};
"1d"

The texture is viewed as a 1-dimensional image.

Corresponding WGSL types:

  • texture_1d

  • texture_storage_1d

"2d"

The texture is viewed as a single 2-dimensional image.

Corresponding WGSL types:

  • texture_2d

  • texture_storage_2d

  • texture_multisampled_2d

  • texture_depth_2d

  • texture_depth_multisampled_2d

"2d-array"

The texture view is viewed as an array of 2-dimensional images.

Corresponding WGSL types:

  • texture_2d_array

  • texture_storage_2d_array

  • texture_depth_2d_array

"cube"

The texture is viewed as a cubemap.

The view has 6 array layers, each corresponding to a face of the cube in the order [+X, -X, +Y, -Y, +Z, -Z] and the following orientations:

Cubemap faces. The +U/+V axes indicate the individual faces' texture coordinates, and thus the texel copy memory layout of each face.

Note: When viewed from the inside, this results in a left-handed coordinate system where +X is right, +Y is up, and +Z is forward.

Sampling is done seamlessly across the faces of the cubemap.

Corresponding WGSL types:

  • texture_cube

  • texture_depth_cube

"cube-array"

The texture is viewed as a packed array of n cubemaps, each with 6 array layers behaving like one "cube" view, for 6n array layers in total.

Corresponding WGSL types:

  • texture_cube_array

  • texture_depth_cube_array

"3d"

The texture is viewed as a 3-dimensional image.

Corresponding WGSL types:

  • texture_3d

  • texture_storage_3d

Each GPUTextureAspect value corresponds to a set of aspects. The set of aspects are defined for each value below.

enum GPUTextureAspect {
    "all",
    "stencil-only",
    "depth-only",
};
"all"

All available aspects of the texture format will be accessible to the texture view. For color formats the color aspect will be accessible. For combined depth-stencil formats both the depth and stencil aspects will be accessible. Depth-or-stencil formats with a single aspect will only make that aspect accessible.

The set of aspects is [color, depth, stencil].

"stencil-only"

Only the stencil aspect of a depth-or-stencil format format will be accessible to the texture view.

The set of aspects is [stencil].

"depth-only"

Only the depth aspect of a depth-or-stencil format format will be accessible to the texture view.

The set of aspects is [depth].

createView(descriptor)

Creates a GPUTextureView.

NOTE:
By default createView() will create a view with a dimension that can represent the entire texture. For example, calling createView() without specifying a dimension on a "2d" texture with more than one layer will create a "2d-array" GPUTextureView, even if an arrayLayerCount of 1 is specified.

For textures created from sources where the layer count is unknown at the time of development it is recommended that calls to createView() are provided with an explicit dimension to ensure shader compatibility.

Called on: GPUTexture this.

Arguments:

Arguments for the GPUTexture.createView(descriptor) method.
Parameter Type Nullable Optional Description
descriptor GPUTextureViewDescriptor Description of the GPUTextureView to create.

Returns: view, of type GPUTextureView.

Content timeline steps:

  1. ? Validate texture format required features of descriptor.format with this.[[device]].

  2. Let view be ! create a new WebGPU object(this, GPUTextureView, descriptor).

  3. Issue the initialization steps on the Device timeline of this.

  4. Return view.

Device timeline initialization steps:
  1. Set descriptor to the result of resolving GPUTextureViewDescriptor defaults for this with descriptor.

  2. If any of the following conditions are unsatisfied generate a validation error, invalidate view and return.

  3. Let view be a new GPUTextureView object.

  4. Set view.[[texture]] to this.

  5. Set view.[[descriptor]] to descriptor.

  6. If descriptor.usage contains RENDER_ATTACHMENT:

    1. Let renderExtent be compute render extent([this.width, this.height, this.depthOrArrayLayers], descriptor.baseMipLevel).

    2. Set view.[[renderExtent]] to renderExtent.

When resolving GPUTextureViewDescriptor defaults for GPUTextureView texture with a GPUTextureViewDescriptor descriptor, run the following device timeline steps:
  1. Let resolved be a copy of descriptor.

  2. If resolved.format is not provided:

    1. Let format be the result of resolving GPUTextureAspect( format, descriptor.aspect).

    2. If format is null:

      Otherwise:

      • Set resolved.format to format.

  3. If resolved.mipLevelCount is not provided: set resolved.mipLevelCount to texture.mipLevelCountresolved.baseMipLevel.

  4. If resolved.dimension is not provided and texture.dimension is:

    "1d"

    Set resolved.dimension to "1d".

    "2d"

    If the array layer count of texture is 1:

    Otherwise:

    "3d"

    Set resolved.dimension to "3d".

  5. If resolved.arrayLayerCount is not provided and resolved.dimension is:

    "1d", "2d", or "3d"

    Set resolved.arrayLayerCount to 1.

    "cube"

    Set resolved.arrayLayerCount to 6.

    "2d-array" or "cube-array"

    Set resolved.arrayLayerCount to the array layer count of textureresolved.baseArrayLayer.

  6. If resolved.usage is 0: set resolved.usage to texture.usage.

  7. Return resolved.

To determine the array layer count of GPUTexture texture, run the following steps:
  1. If texture.dimension is:

    "1d" or "3d"

    Return 1.

    "2d"

    Return texture.depthOrArrayLayers.

6.3. Texture Formats

The name of the format specifies the order of components, bits per component, and data type for the component.

If the format has the -srgb suffix, then sRGB conversions from gamma to linear and vice versa are applied during the reading and writing of color values in the shader. Compressed texture formats are provided by features. Their naming should follow the convention here, with the texture name as a prefix. e.g. etc2-rgba8unorm.

The texel block is a single addressable element of the textures in pixel-based GPUTextureFormats, and a single compressed block of the textures in block-based compressed GPUTextureFormats.

The texel block width and texel block height specifies the dimension of one texel block.

The texel block copy footprint of an aspect of a GPUTextureFormat is the number of bytes one texel block occupies during a texel copy, if applicable.

Note: The texel block memory cost of a GPUTextureFormat is the number of bytes needed to store one texel block. It is not fully defined for all formats. This value is informative and non-normative.

enum GPUTextureFormat {
    // 8-bit formats
    "r8unorm",
    "r8snorm",
    "r8uint",
    "r8sint",

    // 16-bit formats
    "r16unorm",
    "r16snorm",
    "r16uint",
    "r16sint",
    "r16float",
    "rg8unorm",
    "rg8snorm",
    "rg8uint",
    "rg8sint",

    // 32-bit formats
    "r32uint",
    "r32sint",
    "r32float",
    "rg16unorm",
    "rg16snorm",
    "rg16uint",
    "rg16sint",
    "rg16float",
    "rgba8unorm",
    "rgba8unorm-srgb",
    "rgba8snorm",
    "rgba8uint",
    "rgba8sint",
    "bgra8unorm",
    "bgra8unorm-srgb",
    // Packed 32-bit formats
    "rgb9e5ufloat",
    "rgb10a2uint",
    "rgb10a2unorm",
    "rg11b10ufloat",

    // 64-bit formats
    "rg32uint",
    "rg32sint",
    "rg32float",
    "rgba16unorm",
    "rgba16snorm",
    "rgba16uint",
    "rgba16sint",
    "rgba16float",

    // 128-bit formats
    "rgba32uint",
    "rgba32sint",
    "rgba32float",

    // Depth/stencil formats
    "stencil8",
    "depth16unorm",
    "depth24plus",
    "depth24plus-stencil8",
    "depth32float",

    // "depth32float-stencil8" feature
    "depth32float-stencil8",

    // BC compressed formats usable if "texture-compression-bc" is both
    // supported by the device/user agent and enabled in requestDevice.
    "bc1-rgba-unorm",
    "bc1-rgba-unorm-srgb",
    "bc2-rgba-unorm",
    "bc2-rgba-unorm-srgb",
    "bc3-rgba-unorm",
    "bc3-rgba-unorm-srgb",
    "bc4-r-unorm",
    "bc4-r-snorm",
    "bc5-rg-unorm",
    "bc5-rg-snorm",
    "bc6h-rgb-ufloat",
    "bc6h-rgb-float",
    "bc7-rgba-unorm",
    "bc7-rgba-unorm-srgb",

    // ETC2 compressed formats usable if "texture-compression-etc2" is both
    // supported by the device/user agent and enabled in requestDevice.
    "etc2-rgb8unorm",
    "etc2-rgb8unorm-srgb",
    "etc2-rgb8a1unorm",
    "etc2-rgb8a1unorm-srgb",
    "etc2-rgba8unorm",
    "etc2-rgba8unorm-srgb",
    "eac-r11unorm",
    "eac-r11snorm",
    "eac-rg11unorm",
    "eac-rg11snorm",

    // ASTC compressed formats usable if "texture-compression-astc" is both
    // supported by the device/user agent and enabled in requestDevice.
    "astc-4x4-unorm",
    "astc-4x4-unorm-srgb",
    "astc-5x4-unorm",
    "astc-5x4-unorm-srgb",
    "astc-5x5-unorm",
    "astc-5x5-unorm-srgb",
    "astc-6x5-unorm",
    "astc-6x5-unorm-srgb",
    "astc-6x6-unorm",
    "astc-6x6-unorm-srgb",
    "astc-8x5-unorm",
    "astc-8x5-unorm-srgb",
    "astc-8x6-unorm",
    "astc-8x6-unorm-srgb",
    "astc-8x8-unorm",
    "astc-8x8-unorm-srgb",
    "astc-10x5-unorm",
    "astc-10x5-unorm-srgb",
    "astc-10x6-unorm",
    "astc-10x6-unorm-srgb",
    "astc-10x8-unorm",
    "astc-10x8-unorm-srgb",
    "astc-10x10-unorm",
    "astc-10x10-unorm-srgb",
    "astc-12x10-unorm",
    "astc-12x10-unorm-srgb",
    "astc-12x12-unorm",
    "astc-12x12-unorm-srgb",
};

The depth component of the "depth24plus" and "depth24plus-stencil8" formats may be implemented as either a 24-bit depth value or a "depth32float" value.

The stencil8 format may be implemented as either a real "stencil8", or "depth24stencil8", where the depth aspect is hidden and inaccessible.

NOTE:
While the precision of depth32float channels is strictly higher than the precision of 24-bit depth channels for all values in the representable range (0.0 to 1.0), note that the set of representable values is not an exact superset.

A format is renderable if it is either a color renderable format, or a depth-or-stencil format. If a format is listed in § 26.1.1 Plain color formats with RENDER_ATTACHMENT capability, it is a color renderable format. Any other format is not a color renderable format. All depth-or-stencil formats are renderable.

A renderable format is also blendable if it can be used with render pipeline blending. See § 26.1 Texture Format Capabilities.

A format is filterable if it supports the GPUTextureSampleType "float" (not just "unfilterable-float"); that is, it can be used with "filtering" GPUSamplers. See § 26.1 Texture Format Capabilities.

resolving GPUTextureAspect(format, aspect)

Arguments:

Returns: GPUTextureFormat or null

  1. If aspect is:

    "all"

    Return format.

    "depth-only"
    "stencil-only"

    If format is a depth-stencil-format: Return the aspect-specific format of format according to § 26.1.2 Depth-stencil formats or null if the aspect is not present in format.

  2. Return null.

Use of some texture formats require a feature to be enabled on the GPUDevice. Because new formats can be added to the specification, those enum values may not be known by the implementation. In order to normalize behavior across implementations, attempting to use a format that requires a feature will throw an exception if the associated feature is not enabled on the device. This makes the behavior the same as when the format is unknown to the implementation.

See § 26.1 Texture Format Capabilities for information about which GPUTextureFormats require features.

To Validate texture format required features of a GPUTextureFormat format
with logical device device, run the following content timeline steps:
  1. If format requires a feature and device.[[features]] does not contain the feature:

    1. Throw a TypeError.

6.4. GPUExternalTexture

A GPUExternalTexture is a sampleable 2D texture wrapping an external video frame. It is an immutable snapshot; its contents may not change over time, either from inside WebGPU (it is only sampleable) or from outside WebGPU (e.g. due to video frame advancement).

GPUExternalTextures can be bound into bind groups via the externalTexture bind group layout entry member. Note that member uses several binding slots, as defined there.

NOTE:
GPUExternalTexture can be implemented without creating a copy of the imported source, but this depends implementation-defined factors. Ownership of the underlying representation may either be exclusive or shared with other owners (such as a video decoder), but this is not visible to the application.

The underlying representation of an external texture is unobservable (except for precise sampling behavior), but typically may include:

The configuration used internally by an implementation may not be consistent across time, systems, user agents, media sources, or even frames within a single video source. In order to account for many possible representations, the binding conservatively uses the following, for each external texture:

[Exposed=(Window, Worker), SecureContext]
interface GPUExternalTexture {
};
GPUExternalTexture includes GPUObjectBase;

GPUExternalTexture has the following immutable properties:

[[descriptor]], of type GPUExternalTextureDescriptor, readonly

The descriptor with which the texture was created.

GPUExternalTexture has the following immutable properties:

[[expired]], of type boolean, initially false

Indicates whether the object has expired (can no longer be used).

Note: Unlike [[destroyed]] slots, which are similar, this can change from true back to false.

6.4.1. Importing External Textures

An external texture is created from an external video object using importExternalTexture().

An external texture created from an HTMLVideoElement expires (is destroyed) automatically in a task after it is imported, instead of manually or upon garbage collection like other resources. When an external texture expires, its [[expired]] slot changes to true.

An external texture created from a VideoFrame expires (is destroyed) when, and only when, the source VideoFrame is closed, either explicitly by close(), or by other means.

Note: As noted in decode(), authors should call close() on output VideoFrames to avoid decoder stalls. If an imported VideoFrame is dropped without being closed, the imported GPUExternalTexture object will keep it alive until it is also dropped. The VideoFrame cannot be garbage collected until both objects are dropped. Garbage collection is unpredictable, so this may still stall the video decoder.

Once the GPUExternalTexture expires, importExternalTexture() must be called again. However, the user agent may un-expire and return the same GPUExternalTexture again, instead of creating a new one. This will commonly happen unless the execution of the application is scheduled to match the video’s frame rate (e.g. using requestVideoFrameCallback()). If the same object is returned again, it will compare equal, and GPUBindGroups, GPURenderBundles, etc. referencing the previous object can still be used.

dictionary GPUExternalTextureDescriptor
         : GPUObjectDescriptorBase {
    required (HTMLVideoElement or VideoFrame) source;
    PredefinedColorSpace colorSpace = "srgb";
};

GPUExternalTextureDescriptor dictionaries have the following members:

source, of type (HTMLVideoElement or VideoFrame)

The video source to import the external texture from. Source size is determined as described by the external source dimensions table.

colorSpace, of type PredefinedColorSpace, defaulting to "srgb"

The color space the image contents of source will be converted into when reading.

importExternalTexture(descriptor)

Creates a GPUExternalTexture wrapping the provided image source.

Called on: GPUDevice this.

Arguments:

Arguments for the GPUDevice.importExternalTexture(descriptor) method.
Parameter Type Nullable Optional Description
descriptor GPUExternalTextureDescriptor Provides the external image source object (and any creation options).

Returns: GPUExternalTexture

Content timeline steps:

  1. Let source be descriptor.source.

  2. If the current image contents of source are the same as the most recent importExternalTexture() call with the same descriptor (ignoring label), and the user agent chooses to reuse it:

    1. Let previousResult be the GPUExternalTexture returned previously.

    2. Set previousResult.[[expired]] to false, renewing ownership of the underlying resource.

    3. Let result be previousResult.

    Note: This allows the application to detect duplicate imports and avoid re-creating dependent objects (such as GPUBindGroups). Implementations still need to be able to handle a single frame being wrapped by multiple GPUExternalTexture, since import metadata like colorSpace can change even for the same frame.

    Otherwise:

    1. If source is not origin-clean, throw a SecurityError and return.

    2. Let usability be ? check the usability of the image argument(source).

    3. If usability is not good:

      1. Generate a validation error.

      2. Return an invalidated GPUExternalTexture.

    4. Let data be the result of converting the current image contents of source into the color space descriptor.colorSpace with unpremultiplied alpha.

      This may result in values outside of the range [0, 1]. If clamping is desired, it may be performed after sampling.

      Note: This is described like a copy, but may be implemented as a reference to read-only underlying data plus appropriate metadata to perform conversion later.

    5. Let result be a new GPUExternalTexture object wrapping data.

  3. If source is an HTMLVideoElement, queue an automatic expiry task with device this and the following steps:

    1. Set result.[[expired]] to true, releasing ownership of the underlying resource.

    Note: An HTMLVideoElement should be imported in the same task that samples the texture (which should generally be scheduled using requestVideoFrameCallback or requestAnimationFrame() depending on the application). Otherwise, a texture could get destroyed by these steps before the application is finished using it.

  4. If source is a VideoFrame, then when source is closed, run the following steps:

    1. Set result.[[expired]] to true.

  5. Set result.label to descriptor.label.

  6. Return result.

Rendering using an video element external texture at the page animation frame rate:
const videoElement = document.createElement('video');
// ... set up videoElement, wait for it to be ready...

function frame() {
    requestAnimationFrame(frame);

    // Always re-import the video on every animation frame, because the
    // import is likely to have expired.
    // The browser may cache and reuse a past frame, and if it does it
    // may return the same GPUExternalTexture object again.
    // In this case, old bind groups are still valid.
    const externalTexture = gpuDevice.importExternalTexture({
        source: videoElement
    });

    // ... render using externalTexture...
}
requestAnimationFrame(frame);
Rendering using an video element external texture at the video’s frame rate, if requestVideoFrameCallback is available:
const videoElement = document.createElement('video');
// ... set up videoElement...

function frame() {
    videoElement.requestVideoFrameCallback(frame);

    // Always re-import, because we know the video frame has advanced
    const externalTexture = gpuDevice.importExternalTexture({
        source: videoElement
    });

    // ... render using externalTexture...
}
videoElement.requestVideoFrameCallback(frame);

6.5. Sampling External Texture Bindings

The externalTexture binding point allows binding GPUExternalTexture objects (from dynamic image sources like videos). It also supports GPUTexture and GPUTextureView.

Note: When a GPUTexture or a GPUTextureView is bound to an externalTexture binding, it is like a GPUExternalTexture with a single RGBA plane and no crop, rotation, or color conversion.

External textures are represented in WGSL with texture_external and may be read using textureLoad and textureSampleBaseClampToEdge.

The sampler provided to textureSampleBaseClampToEdge is used to sample the underlying textures.

When the binding resource type is a GPUExternalTexture, the result is in the color space set by colorSpace. It is implementation-dependent whether, for any given external texture, the sampler (and filtering) is applied before or after conversion from underlying values into the specified color space.

Note: If the internal representation is an RGBA plane, sampling behaves as on a regular 2D texture. If there are several underlying planes (e.g. Y+UV), the sampler is used to sample each underlying texture separately, prior to conversion from YUV to the specified color space.

7. Samplers

7.1. GPUSampler

A GPUSampler encodes transformations and filtering information that can be used in a shader to interpret texture resource data.

GPUSamplers are created via createSampler().

[Exposed=(Window, Worker), SecureContext]
interface GPUSampler {
};
GPUSampler includes GPUObjectBase;

GPUSampler has the following immutable properties:

[[descriptor]], of type GPUSamplerDescriptor, readonly

The GPUSamplerDescriptor with which the GPUSampler was created.

[[isComparison]], of type boolean, readonly

Whether the GPUSampler is used as a comparison sampler.

[[isFiltering]], of type boolean, readonly

Whether the GPUSampler weights multiple samples of a texture.

7.1.1. GPUSamplerDescriptor

A GPUSamplerDescriptor specifies the options to use to create a GPUSampler.

dictionary GPUSamplerDescriptor
         : GPUObjectDescriptorBase {
    GPUAddressMode addressModeU = "clamp-to-edge";
    GPUAddressMode addressModeV = "clamp-to-edge";
    GPUAddressMode addressModeW = "clamp-to-edge";
    GPUFilterMode magFilter = "nearest";
    GPUFilterMode minFilter = "nearest";
    GPUMipmapFilterMode mipmapFilter = "nearest";
    float lodMinClamp = 0;
    float lodMaxClamp = 32;
    GPUCompareFunction compare;
    [Clamp] unsigned short maxAnisotropy = 1;
};
addressModeU, of type GPUAddressMode, defaulting to "clamp-to-edge"
addressModeV, of type GPUAddressMode, defaulting to "clamp-to-edge"
addressModeW, of type GPUAddressMode, defaulting to "clamp-to-edge"

Specifies the address modes for the texture width, height, and depth coordinates, respectively.

magFilter, of type GPUFilterMode, defaulting to "nearest"

Specifies the sampling behavior when the sampled area is smaller than or equal to one texel.

minFilter, of type GPUFilterMode, defaulting to "nearest"

Specifies the sampling behavior when the sampled area is larger than one texel.

mipmapFilter, of type GPUMipmapFilterMode, defaulting to "nearest"

Specifies behavior for sampling between mipmap levels.

lodMinClamp, of type float, defaulting to 0
lodMaxClamp, of type float, defaulting to 32

Specifies the minimum and maximum levels of detail, respectively, used internally when sampling a texture.

compare, of type GPUCompareFunction

When provided the sampler will be a comparison sampler with the specified GPUCompareFunction.

Note: Comparison samplers may use filtering, but the sampling results will be implementation-dependent and may differ from the normal filtering rules.

maxAnisotropy, of type unsigned short, defaulting to 1

Specifies the maximum anisotropy value clamp used by the sampler. Anisotropic filtering is enabled when maxAnisotropy is > 1 and the implementation supports it.

Anisotropic filtering improves the image quality of textures sampled at oblique viewing angles. Higher maxAnisotropy values indicate the maximum ratio of anisotropy supported when filtering.

NOTE:
Most implementations support maxAnisotropy values in range between 1 and 16, inclusive. The used value of maxAnisotropy will be clamped to the maximum value that the platform supports.

The precise filtering behavior is implementation-dependent.

Level of detail (LOD) describes which mip level(s) are selected when sampling a texture. It may be specified explicitly through shader methods like textureSampleLevel or implicitly determined from the texture coordinate derivatives.

Note: See Scale Factor Operation, LOD Operation and Image Level Selection in the Vulkan 1.3 spec for an example of how implicit LODs may be calculated.

GPUAddressMode describes the behavior of the sampler if the sampled texels extend beyond the bounds of the sampled texture.

enum GPUAddressMode {
    "clamp-to-edge",
    "repeat",
    "mirror-repeat",
};
"clamp-to-edge"

Texture coordinates are clamped between 0.0 and 1.0, inclusive.

"repeat"

Texture coordinates wrap to the other side of the texture.

"mirror-repeat"

Texture coordinates wrap to the other side of the texture, but the texture is flipped when the integer part of the coordinate is odd.

GPUFilterMode and GPUMipmapFilterMode describe the behavior of the sampler if the sampled area does not cover exactly one texel.

Note: See Texel Filtering in the Vulkan 1.3 spec for an example of how samplers may determine which texels are sampled from for the various filtering modes.

enum GPUFilterMode {
    "nearest",
    "linear",
};

enum GPUMipmapFilterMode {
    "nearest",
    "linear",
};
"nearest"

Return the value of the texel nearest to the texture coordinates.

"linear"

Select two texels in each dimension and return a linear interpolation between their values.

GPUCompareFunction specifies the behavior of a comparison sampler. If a comparison sampler is used in a shader, the depth_ref is compared to the fetched texel value, and the result of this comparison test is generated (1.0f for pass, or 0.0f for fail).

After comparison, if texture filtering is enabled, the filtering step occurs, so that comparison results are mixed together resulting in values in the range [0, 1]. Filtering should behave as usual, however it may be computed with lower precision or not mix results at all.

enum GPUCompareFunction {
    "never",
    "less",
    "equal",
    "less-equal",
    "greater",
    "not-equal",
    "greater-equal",
    "always",
};
"never"

Comparison tests never pass.

"less"

A provided value passes the comparison test if it is less than the sampled value.

"equal"

A provided value passes the comparison test if it is equal to the sampled value.

"less-equal"

A provided value passes the comparison test if it is less than or equal to the sampled value.

"greater"

A provided value passes the comparison test if it is greater than the sampled value.

"not-equal"

A provided value passes the comparison test if it is not equal to the sampled value.

"greater-equal"

A provided value passes the comparison test if it is greater than or equal to the sampled value.

"always"

Comparison tests always pass.

7.1.2. Sampler Creation

createSampler(descriptor)

Creates a GPUSampler.

Called on: GPUDevice this.

Arguments:

Arguments for the GPUDevice.createSampler(descriptor) method.
Parameter Type Nullable Optional Description
descriptor GPUSamplerDescriptor Description of the GPUSampler to create.

Returns: GPUSampler

Content timeline steps:

  1. Let s be ! create a new WebGPU object(this, GPUSampler, descriptor).

  2. Issue the initialization steps on the Device timeline of this.

  3. Return s.

Device timeline initialization steps:
  1. If any of the following conditions are unsatisfied generate a validation error, invalidate s and return.

  2. Set s.[[descriptor]] to descriptor.

  3. Set s.[[isComparison]] to false if the compare attribute of s.[[descriptor]] is null or undefined. Otherwise, set it to true.

  4. Set s.[[isFiltering]] to false if none of minFilter, magFilter, or mipmapFilter has the value of "linear". Otherwise, set it to true.

Creating a GPUSampler that does trilinear filtering and repeats texture coordinates:
const sampler = gpuDevice.createSampler({
    addressModeU: 'repeat',
    addressModeV: 'repeat',
    magFilter: 'linear',
    minFilter: 'linear',
    mipmapFilter: 'linear',
});

8. Resource Binding

8.1. GPUBindGroupLayout

A GPUBindGroupLayout defines the interface between a set of resources bound in a GPUBindGroup and their accessibility in shader stages.

[Exposed=(Window, Worker), SecureContext]
interface GPUBindGroupLayout {
};
GPUBindGroupLayout includes GPUObjectBase;

GPUBindGroupLayout has the following immutable properties:

[[descriptor]], of type GPUBindGroupLayoutDescriptor, readonly

8.1.1. Bind Group Layout Creation

A GPUBindGroupLayout is created via GPUDevice.createBindGroupLayout().

dictionary GPUBindGroupLayoutDescriptor
         : GPUObjectDescriptorBase {
    required sequence<GPUBindGroupLayoutEntry> entries;
};

GPUBindGroupLayoutDescriptor dictionaries have the following members:

entries, of type sequence<GPUBindGroupLayoutEntry>

A list of entries describing the shader resource bindings for a bind group.

A GPUBindGroupLayoutEntry describes a single shader resource binding to be included in a GPUBindGroupLayout.

dictionary GPUBindGroupLayoutEntry {
    required GPUIndex32 binding;
    required GPUShaderStageFlags visibility;

    GPUBufferBindingLayout buffer;
    GPUSamplerBindingLayout sampler;
    GPUTextureBindingLayout texture;
    GPUStorageTextureBindingLayout storageTexture;
    GPUExternalTextureBindingLayout externalTexture;
};

GPUBindGroupLayoutEntry dictionaries have the following members:

binding, of type GPUIndex32

A unique identifier for a resource binding within the GPUBindGroupLayout, corresponding to a GPUBindGroupEntry.binding and a @binding attribute in the GPUShaderModule.

visibility, of type GPUShaderStageFlags

A bitset of the members of GPUShaderStage. Each set bit indicates that a GPUBindGroupLayoutEntry’s resource will be accessible from the associated shader stage.

buffer, of type GPUBufferBindingLayout
sampler, of type GPUSamplerBindingLayout
texture, of type GPUTextureBindingLayout
storageTexture, of type GPUStorageTextureBindingLayout
externalTexture, of type GPUExternalTextureBindingLayout

Exactly one of these members must be set, indicating the binding type. The contents of the member specify options specific to that type.

The corresponding resource in createBindGroup() requires the corresponding binding resource type for this binding.

typedef [EnforceRange] unsigned long GPUShaderStageFlags;
[Exposed=(Window, Worker), SecureContext]
namespace GPUShaderStage {
    const GPUFlagsConstant VERTEX   = 0x1;
    const GPUFlagsConstant FRAGMENT = 0x2;
    const GPUFlagsConstant COMPUTE  = 0x4;
};

GPUShaderStage contains the following flags, which describe which shader stages a corresponding GPUBindGroupEntry for this GPUBindGroupLayoutEntry will be visible to:

VERTEX

The bind group entry will be accessible to vertex shaders.

FRAGMENT

The bind group entry will be accessible to fragment shaders.

COMPUTE

The bind group entry will be accessible to compute shaders.

The binding member of a GPUBindGroupLayoutEntry is determined by which member of the GPUBindGroupLayoutEntry is defined: buffer, sampler, texture, storageTexture, or externalTexture. Only one may be defined for any given GPUBindGroupLayoutEntry. Each member has an associated GPUBindingResource type and each binding type has an associated internal usage, given by this table:

Binding member Resource type Binding type
Binding usage
buffer GPUBufferBinding
(or GPUBuffer as shorthand)
"uniform" constant
"storage" storage
"read-only-storage" storage-read
sampler GPUSampler "filtering" constant
"non-filtering"
"comparison"
texture GPUTextureView
(or GPUTexture as shorthand)
"float" constant
"unfilterable-float"
"depth"
"sint"
"uint"
storageTexture GPUTextureView
(or GPUTexture as shorthand)
"write-only" storage
"read-write"
"read-only" storage-read
externalTexture GPUExternalTexture
or GPUTextureView
(or GPUTexture as shorthand)
constant
The list of GPUBindGroupLayoutEntry values entries exceeds the binding slot limits of supported limits limits if the number of slots used toward a limit exceeds the supported value in limits. Each entry may use multiple slots toward multiple limits.

Device timeline steps:

  1. For each entry in entries, if:

    entry.buffer?.type is "uniform" and entry.buffer?.hasDynamicOffset is true

    Consider 1 maxDynamicUniformBuffersPerPipelineLayout slot to be used.

    entry.buffer?.type is "storage" and entry.buffer?.hasDynamicOffset is true

    Consider 1 maxDynamicStorageBuffersPerPipelineLayout slot to be used.

  2. For each shader stage stage in « VERTEX, FRAGMENT, COMPUTE »:

    1. For each entry in entries for which entry.visibility contains stage, if:

      entry.buffer?.type is "uniform"

      Consider 1 maxUniformBuffersPerShaderStage slot to be used.

      entry.buffer?.type is "storage" or "read-only-storage"

      Consider 1 maxStorageBuffersPerShaderStage slot to be used.

      entry.sampler is provided

      Consider 1 maxSamplersPerShaderStage slot to be used.

      entry.texture is provided

      Consider 1 maxSampledTexturesPerShaderStage slot to be used.

      entry.storageTexture is provided

      Consider 1 maxStorageTexturesPerShaderStage slot to be used.

      entry.externalTexture is provided

      Consider 4 maxSampledTexturesPerShaderStage slot, 1 maxSamplersPerShaderStage slot, and 1 maxUniformBuffersPerShaderStage slot to be used.

      Note: See GPUExternalTexture for an explanation of this behavior.

enum GPUBufferBindingType {
    "uniform",
    "storage",
    "read-only-storage",
};

dictionary GPUBufferBindingLayout {
    GPUBufferBindingType type = "uniform";
    boolean hasDynamicOffset = false;
    GPUSize64 minBindingSize = 0;
};

GPUBufferBindingLayout dictionaries have the following members:

type, of type GPUBufferBindingType, defaulting to "uniform"

Indicates the type required for buffers bound to this bindings.

hasDynamicOffset, of type boolean, defaulting to false

Indicates whether this binding requires a dynamic offset.

minBindingSize, of type GPUSize64, defaulting to 0

Indicates the minimum size of a buffer binding used with this bind point.

Bindings are always validated against this size in createBindGroup().

If this is not 0, pipeline creation additionally validates that this value ≥ the minimum buffer binding size of the variable.

If this is 0, it is ignored by pipeline creation, and instead draw/dispatch commands validate that each binding in the GPUBindGroup satisfies the minimum buffer binding size of the variable.

Note: Similar execution-time validation is theoretically possible for other binding-related fields specified for early validation, like sampleType and format, which currently can only be validated in pipeline creation. However, such execution-time validation could be costly or unnecessarily complex, so it is available only for minBindingSize which is expected to have the most ergonomic impact.

enum GPUSamplerBindingType {
    "filtering",
    "non-filtering",
    "comparison",
};

dictionary GPUSamplerBindingLayout {
    GPUSamplerBindingType type = "filtering";
};

GPUSamplerBindingLayout dictionaries have the following members:

type, of type GPUSamplerBindingType, defaulting to "filtering"

Indicates the required type of a sampler bound to this bindings.

enum GPUTextureSampleType {
    "float",
    "unfilterable-float",
    "depth",
    "sint",
    "uint",
};

dictionary GPUTextureBindingLayout {
    GPUTextureSampleType sampleType = "float";
    GPUTextureViewDimension viewDimension = "2d";
    boolean multisampled = false;
};

GPUTextureBindingLayout dictionaries have the following members:

sampleType, of type GPUTextureSampleType, defaulting to "float"

Indicates the type required for texture views bound to this binding.

viewDimension, of type GPUTextureViewDimension, defaulting to "2d"

Indicates the required dimension for texture views bound to this binding.

multisampled, of type boolean, defaulting to false

Indicates whether or not texture views bound to this binding must be multisampled.

enum GPUStorageTextureAccess {
    "write-only",
    "read-only",
    "read-write",
};

dictionary GPUStorageTextureBindingLayout {
    GPUStorageTextureAccess access = "write-only";
    required GPUTextureFormat format;
    GPUTextureViewDimension viewDimension = "2d";
};

GPUStorageTextureBindingLayout dictionaries have the following members:

access, of type GPUStorageTextureAccess, defaulting to "write-only"

The access mode for this binding, indicating readability and writability.

format, of type GPUTextureFormat

The required format of texture views bound to this binding.

viewDimension, of type GPUTextureViewDimension, defaulting to "2d"

Indicates the required dimension for texture views bound to this binding.

dictionary GPUExternalTextureBindingLayout {
};

A GPUBindGroupLayout object has the following device timeline properties:

[[entryMap]], of type ordered map<GPUSize32, GPUBindGroupLayoutEntry>, readonly

The map of binding indices pointing to the GPUBindGroupLayoutEntrys, which this GPUBindGroupLayout describes.

[[dynamicOffsetCount]], of type GPUSize32, readonly

The number of buffer bindings with dynamic offsets in this GPUBindGroupLayout.

[[exclusivePipeline]], of type GPUPipelineBase?, readonly

The pipeline that created this GPUBindGroupLayout, if it was created as part of a default pipeline layout. If not null, GPUBindGroups created with this GPUBindGroupLayout can only be used with the specified GPUPipelineBase.

createBindGroupLayout(descriptor)

Creates a GPUBindGroupLayout.

Called on: GPUDevice this.

Arguments:

Arguments for the GPUDevice.createBindGroupLayout(descriptor) method.
Parameter Type Nullable Optional Description
descriptor GPUBindGroupLayoutDescriptor Description of the GPUBindGroupLayout to create.

Returns: GPUBindGroupLayout

Content timeline steps:

  1. For each GPUBindGroupLayoutEntry entry in descriptor.entries:

    1. If entry.storageTexture is provided:

      1. ? Validate texture format required features for entry.storageTexture.format with this.[[device]].

  2. Let layout be ! create a new WebGPU object(this, GPUBindGroupLayout, descriptor).

  3. Issue the initialization steps on the Device timeline of this.

  4. Return layout.

Device timeline initialization steps:
  1. If any of the following conditions are unsatisfied generate a validation error, invalidate layout and return.

  2. Set layout.[[descriptor]] to descriptor.

  3. Set layout.[[dynamicOffsetCount]] to the number of entries in descriptor where buffer is provided and buffer.hasDynamicOffset is true.

  4. Set layout.[[exclusivePipeline]] to null.

  5. For each GPUBindGroupLayoutEntry entry in descriptor.entries:

    1. Insert entry into layout.[[entryMap]] with the key of entry.binding.

8.1.2. Compatibility

Two GPUBindGroupLayout objects a and b are considered group-equivalent if and only if all of the following conditions are satisfied:

If bind groups layouts are group-equivalent they can be interchangeably used in all contents.

8.2. GPUBindGroup

A GPUBindGroup defines a set of resources to be bound together in a group and how the resources are used in shader stages.

[Exposed=(Window, Worker), SecureContext]
interface GPUBindGroup {
};
GPUBindGroup includes GPUObjectBase;

GPUBindGroup has the following device timeline properties:

[[layout]], of type GPUBindGroupLayout, readonly

The GPUBindGroupLayout associated with this GPUBindGroup.

[[entries]], of type sequence<GPUBindGroupEntry>, readonly

The set of GPUBindGroupEntrys this GPUBindGroup describes.

[[usedResources]], of type usage scope, readonly

The set of buffer and texture subresources used by this bind group, associated with lists of the internal usage flags.

The bound buffer ranges of a GPUBindGroup bindGroup, given list<GPUBufferDynamicOffset> dynamicOffsets, are computed as follows:
  1. Let result be a new set<(GPUBindGroupLayoutEntry, GPUBufferBinding)>.

  2. Let dynamicOffsetIndex be 0.

  3. For each GPUBindGroupEntry bindGroupEntry in bindGroup.[[entries]], sorted by bindGroupEntry.binding:

    1. Let bindGroupLayoutEntry be bindGroup.[[layout]].[[entryMap]][bindGroupEntry.binding].

    2. If bindGroupLayoutEntry.buffer is not provided, continue.

    3. Let bound be get as buffer binding(bindGroupEntry.resource).

    4. If bindGroupLayoutEntry.buffer.hasDynamicOffset:

      1. Increment bound.offset by dynamicOffsets[dynamicOffsetIndex].

      2. Increment dynamicOffsetIndex by 1.

    5. Append (bindGroupLayoutEntry, bound) to result.

  4. Return result.

8.2.1. Bind Group Creation

A GPUBindGroup is created via GPUDevice.createBindGroup().

dictionary GPUBindGroupDescriptor
         : GPUObjectDescriptorBase {
    required GPUBindGroupLayout layout;
    required sequence<GPUBindGroupEntry> entries;
};

GPUBindGroupDescriptor dictionaries have the following members:

layout, of type GPUBindGroupLayout

The GPUBindGroupLayout the entries of this bind group will conform to.

entries, of type sequence<GPUBindGroupEntry>

A list of entries describing the resources to expose to the shader for each binding described by the layout.

typedef (GPUSampler or
         GPUTexture or
         GPUTextureView or
         GPUBuffer or
         GPUBufferBinding or
         GPUExternalTexture) GPUBindingResource;

dictionary GPUBindGroupEntry {
    required GPUIndex32 binding;
    required GPUBindingResource resource;
};

A GPUBindGroupEntry describes a single resource to be bound in a GPUBindGroup, and has the following members:

binding, of type GPUIndex32

A unique identifier for a resource binding within the GPUBindGroup, corresponding to a GPUBindGroupLayoutEntry.binding and a @binding attribute in the GPUShaderModule.

resource, of type GPUBindingResource

The resource to bind, which may be a GPUSampler, GPUTexture, GPUTextureView, GPUBuffer, GPUBufferBinding, or GPUExternalTexture.

GPUBindGroupEntry has the following device timeline properties:

[[prevalidatedSize]], of type boolean

Whether or not this binding entry had its buffer size validated at time of creation.

dictionary GPUBufferBinding {
    required GPUBuffer buffer;
    GPUSize64 offset = 0;
    GPUSize64 size;
};

A GPUBufferBinding describes a buffer and optional range to bind as a resource, and has the following members:

buffer, of type GPUBuffer

The GPUBuffer to bind.

offset, of type GPUSize64, defaulting to 0

The offset, in bytes, from the beginning of buffer to the beginning of the range exposed to the shader by the buffer binding.

size, of type GPUSize64

The size, in bytes, of the buffer binding. If not provided, specifies the range starting at offset and ending at the end of buffer.

createBindGroup(descriptor)

Creates a GPUBindGroup.

Called on: GPUDevice this.

Arguments:

Arguments for the GPUDevice.createBindGroup(descriptor) method.
Parameter Type Nullable Optional Description
descriptor GPUBindGroupDescriptor Description of the GPUBindGroup to create.

Returns: GPUBindGroup

Content timeline steps:

  1. Let bindGroup be ! create a new WebGPU object(this, GPUBindGroup, descriptor).

  2. Issue the initialization steps on the Device timeline of this.

  3. Return bindGroup.

Device timeline initialization steps:
  1. Let limits be this.[[device]].[[limits]].

  2. If any of the following conditions are unsatisfied generate a validation error, invalidate bindGroup and return.

    For each GPUBindGroupEntry bindingDescriptor in descriptor.entries:

  3. Let bindGroup.[[layout]] = descriptor.layout.

  4. Let bindGroup.[[entries]] = descriptor.entries.

  5. Let bindGroup.[[usedResources]] = {}.

  6. For each GPUBindGroupEntry bindingDescriptor in descriptor.entries:

    1. Let internalUsage be the binding usage for layoutBinding.

    2. Each subresource seen by resource is added to [[usedResources]] as internalUsage.

    3. Let bindingDescriptor.[[prevalidatedSize]] be false if the defined binding member for layoutBinding is buffer and layoutBinding.buffer.minBindingSize is 0, and true otherwise.

get as texture view(resource)

Arguments:

Returns: GPUTextureView

  1. Assert resource is either a GPUTexture or a GPUTextureView.

  2. If resource is a:

    GPUTexture
    1. Return resource.createView().

    GPUTextureView
    1. Return resource.

get as buffer binding(resource)

Arguments:

Returns: GPUBufferBinding

  1. Assert resource is either a GPUBuffer or a GPUBufferBinding.

  2. If resource is a:

    GPUBuffer
    1. Let bufferBinding a new GPUBufferBinding.

    2. Set bufferBinding.buffer to resource.

    3. Return bufferBinding.

    GPUBufferBinding
    1. Return resource.

effective buffer binding size(binding)

Arguments:

Returns: GPUSize64

  1. If binding.size is not provided:

    1. Return max(0, binding.buffer.size - binding.offset);

  2. Return binding.size.

Two GPUBufferBinding objects a and b are considered buffer-binding-aliasing if and only if all of the following are true:

Note: When doing this calculation, any dynamic offsets have already been applied to the ranges.

8.3. GPUPipelineLayout

A GPUPipelineLayout defines the mapping between resources of all GPUBindGroup objects set up during command encoding in setBindGroup(), and the shaders of the pipeline set by GPURenderCommandsMixin.setPipeline or GPUComputePassEncoder.setPipeline.

The full binding address of a resource can be defined as a trio of:

  1. shader stage mask, to which the resource is visible

  2. bind group index

  3. binding number

The components of this address can also be seen as the binding space of a pipeline. A GPUBindGroup (with the corresponding GPUBindGroupLayout) covers that space for a fixed bind group index. The contained bindings need to be a superset of the resources used by the shader at this bind group index.

[Exposed=(Window, Worker), SecureContext]
interface GPUPipelineLayout {
};
GPUPipelineLayout includes GPUObjectBase;

GPUPipelineLayout has the following device timeline properties:

[[bindGroupLayouts]], of type list<GPUBindGroupLayout>, readonly

The GPUBindGroupLayout objects provided at creation in GPUPipelineLayoutDescriptor.bindGroupLayouts.

Note: using the same GPUPipelineLayout for many GPURenderPipeline or GPUComputePipeline pipelines guarantees that the user agent doesn’t need to rebind any resources internally when there is a switch between these pipelines.

GPUComputePipeline object X was created with GPUPipelineLayout.bindGroupLayouts A, B, C. GPUComputePipeline object Y was created with GPUPipelineLayout.bindGroupLayouts A, D, C. Supposing the command encoding sequence has two dispatches:
  1. setBindGroup(0, ...)

  2. setBindGroup(1, ...)

  3. setBindGroup(2, ...)

  4. setPipeline(X)

  5. dispatchWorkgroups()

  6. setBindGroup(1, ...)

  7. setPipeline(Y)

  8. dispatchWorkgroups()

In this scenario, the user agent would have to re-bind the group slot 2 for the second dispatch, even though neither the GPUBindGroupLayout at index 2 of GPUPipelineLayout.bindGroupLayouts, or the GPUBindGroup at slot 2, change.

Note: the expected usage of the GPUPipelineLayout is placing the most common and the least frequently changing bind groups at the "bottom" of the layout, meaning lower bind group slot numbers, like 0 or 1. The more frequently a bind group needs to change between draw calls, the higher its index should be. This general guideline allows the user agent to minimize state changes between draw calls, and consequently lower the CPU overhead.

8.3.1. Pipeline Layout Creation

A GPUPipelineLayout is created via GPUDevice.createPipelineLayout().

dictionary GPUPipelineLayoutDescriptor
         : GPUObjectDescriptorBase {
    required sequence<GPUBindGroupLayout?> bindGroupLayouts;
};

GPUPipelineLayoutDescriptor dictionaries define all the GPUBindGroupLayouts used by a pipeline, and have the following members:

bindGroupLayouts, of type sequence<GPUBindGroupLayout?>

A list of optional GPUBindGroupLayouts the pipeline will use. Each element corresponds to a @group attribute in the GPUShaderModule, with the Nth element corresponding with @group(N).

createPipelineLayout(descriptor)

Creates a GPUPipelineLayout.

Called on: GPUDevice this.

Arguments:

Arguments for the GPUDevice.createPipelineLayout(descriptor) method.
Parameter Type Nullable Optional Description
descriptor GPUPipelineLayoutDescriptor Description of the GPUPipelineLayout to create.

Returns: GPUPipelineLayout

Content timeline steps:

  1. Let pl be ! create a new WebGPU object(this, GPUPipelineLayout, descriptor).

  2. Issue the initialization steps on the Device timeline of this.

  3. Return pl.

Device timeline initialization steps:
  1. Let limits be this.[[device]].[[limits]].

  2. Let bindGroupLayouts be a list of null GPUBindGroupLayouts with size equal to limits.maxBindGroups.

  3. For each bindGroupLayout at index i in descriptor.bindGroupLayouts:

    1. If bindGroupLayout is not null and bindGroupLayout.[[descriptor]].entries is not empty:

      1. Set bindGroupLayouts[i] to bindGroupLayout.

  4. Let allEntries be the result of concatenating bgl.[[descriptor]].entries for all non-null bgl in bindGroupLayouts.

  5. If any of the following conditions are unsatisfied generate a validation error, invalidate pl and return.

  6. Set the pl.[[bindGroupLayouts]] to bindGroupLayouts.

Note: two GPUPipelineLayout objects are considered equivalent for any usage if their internal [[bindGroupLayouts]] sequences contain GPUBindGroupLayout objects that are group-equivalent.

8.4. Example

Create a GPUBindGroupLayout that describes a binding with a uniform buffer, a texture, and a sampler. Then create a GPUBindGroup and a GPUPipelineLayout using the GPUBindGroupLayout.
const bindGroupLayout = gpuDevice.createBindGroupLayout({
    entries: [{
        binding: 0,
        visibility: GPUShaderStage.VERTEX | GPUShaderStage.FRAGMENT,
        buffer: {}
    }, {
        binding: 1,
        visibility: GPUShaderStage.FRAGMENT,
        texture: {}
    }, {
        binding: 2,
        visibility: GPUShaderStage.FRAGMENT,
        sampler: {}
    }]
});

const bindGroup = gpuDevice.createBindGroup({
    layout: bindGroupLayout,
    entries: [{
        binding: 0,
        resource: { buffer: buffer },
    }, {
        binding: 1,
        resource: texture
    }, {
        binding: 2,
        resource: sampler
    }]
});

const pipelineLayout = gpuDevice.createPipelineLayout({
    bindGroupLayouts: [bindGroupLayout]
});

9. Shader Modules

9.1. GPUShaderModule

[Exposed=(Window, Worker), SecureContext]
interface GPUShaderModule {
    Promise<GPUCompilationInfo> getCompilationInfo();
};
GPUShaderModule includes GPUObjectBase;

GPUShaderModule is a reference to an internal shader module object.

9.1.1. Shader Module Creation

dictionary GPUShaderModuleDescriptor
         : GPUObjectDescriptorBase {
    required USVString code;
    sequence<GPUShaderModuleCompilationHint> compilationHints = [];
};
code, of type USVString

The WGSL source code for the shader module.

compilationHints, of type sequence<GPUShaderModuleCompilationHint>, defaulting to []

A list of GPUShaderModuleCompilationHints.

Any hint provided by an application should contain information about one entry point of a pipeline that will eventually be created from the entry point.

Implementations should use any information present in the GPUShaderModuleCompilationHint to perform as much compilation as is possible within createShaderModule().

Aside from type-checking, these hints are not validated in any way.

NOTE:
Supplying information in compilationHints does not have any observable effect, other than performance. It may be detrimental to performance to provide hints for pipelines that never end up being created.

Because a single shader module can hold multiple entry points, and multiple pipelines can be created from a single shader module, it can be more performant for an implementation to do as much compilation as possible once in createShaderModule() rather than multiple times in the multiple calls to createComputePipeline() or createRenderPipeline().

Hints are only applied to the entry points they explicitly name. Unlike GPUProgrammableStage.entryPoint, there is no default, even if only one entry point is present in the module.

Note: Hints are not validated in an observable way, but user agents may surface identifiable errors (like unknown entry point names or incompatible pipeline layouts) to developers, for example in the browser developer console.

createShaderModule(descriptor)

Creates a GPUShaderModule.

Called on: GPUDevice this.

Arguments:

Arguments for the GPUDevice.createShaderModule(descriptor) method.
Parameter Type Nullable Optional Description
descriptor GPUShaderModuleDescriptor Description of the GPUShaderModule to create.

Returns: GPUShaderModule

Content timeline steps:

  1. Let sm be ! create a new WebGPU object(this, GPUShaderModule, descriptor).

  2. Issue the initialization steps on the Device timeline of this.

  3. Return sm.

Device timeline initialization steps:
  1. Let error be any error that results from shader module creation with the WGSL source descriptor.code, or null if no errors occured.

  2. If any of the following requirements are unmet, generate a validation error, invalidate sm, and return.

    Note: Uncategorized errors cannot arise from shader module creation. Implementations which detect such errors during shader module creation must behave as if the shader module is valid, and defer surfacing the error until pipeline creation.

NOTE:
User agents should not include detailed compiler error messages or shader text in the message text of validation errors arising here: these details are accessible via getCompilationInfo(). User agents should surface human-readable, formatted error details to developers for easier debugging (for example as a warning in the browser developer console, expandable to show full shader source).

As shader compilation errors should be rare in production applications, user agents could choose to surface them to developers regardless of error handling (GPU error scopes or uncapturederror event handlers), e.g. as an expandable warning. If not, they should provide and document another way for developers to access human-readable error details, for example by adding a checkbox to show errors unconditionally, or by showing human-readable details when logging a GPUCompilationInfo object to the console.

Create a GPUShaderModule from WGSL code:
// A simple vertex and fragment shader pair that will fill the viewport with red.
const shaderSource = `
    var<private> pos : array<vec2<f32>, 3> = array<vec2<f32>, 3>(
        vec2(-1.0, -1.0), vec2(-1.0, 3.0), vec2(3.0, -1.0));

    @vertex
    fn vertexMain(@builtin(vertex_index) vertexIndex : u32) -> @builtin(position) vec4<f32> {
        return vec4(pos[vertexIndex], 1.0, 1.0);
    }

    @fragment
    fn fragmentMain() -> @location(0) vec4<f32> {
        return vec4(1.0, 0.0, 0.0, 1.0);
    }
`;

const shaderModule = gpuDevice.createShaderModule({
    code: shaderSource,
});
9.1.1.1. Shader Module Compilation Hints

Shader module compilation hints are optional, additional information indicating how a given GPUShaderModule entry point is intended to be used in the future. For some implementations this information may aid in compiling the shader module earlier, potentially increasing performance.

dictionary GPUShaderModuleCompilationHint {
    required USVString entryPoint;
    (GPUPipelineLayout or GPUAutoLayoutMode) layout;
};
layout, of type (GPUPipelineLayout or GPUAutoLayoutMode)

A GPUPipelineLayout that the GPUShaderModule may be used with in a future createComputePipeline() or createRenderPipeline() call. If set to "auto" the layout will be the default pipeline layout for the entry point associated with this hint will be used.

NOTE:
If possible, authors should be supplying the same information to createShaderModule() and createComputePipeline() / createRenderPipeline().

If an application is unable to provide hint information at the time of calling createShaderModule(), it should usually not delay calling createShaderModule(), but instead just omit the unknown information from the compilationHints sequence or the individual members of GPUShaderModuleCompilationHint. Omitting this information may cause compilation to be deferred to createComputePipeline() / createRenderPipeline().

If an author is not confident that the hint information passed to createShaderModule() will match the information later passed to createComputePipeline() / createRenderPipeline() with that same module, they should avoid passing that information to createShaderModule(), as passing mismatched information to createShaderModule() may cause unnecessary compilations to occur.

9.1.2. Shader Module Compilation Information

enum GPUCompilationMessageType {
    "error",
    "warning",
    "info",
};

[Exposed=(Window, Worker), Serializable, SecureContext]
interface GPUCompilationMessage {
    readonly attribute DOMString message;
    readonly attribute GPUCompilationMessageType type;
    readonly attribute unsigned long long lineNum;
    readonly attribute unsigned long long linePos;
    readonly attribute unsigned long long offset;
    readonly attribute unsigned long long length;
};

[Exposed=(Window, Worker), Serializable, SecureContext]
interface GPUCompilationInfo {
    readonly attribute FrozenArray<GPUCompilationMessage> messages;
};

A GPUCompilationMessage is an informational, warning, or error message generated by the GPUShaderModule compiler. The messages are intended to be human readable to help developers diagnose issues with their shader code. Each message may correspond to either a single point in the shader code, a substring of the shader code, or may not correspond to any specific point in the code at all.

GPUCompilationMessage has the following attributes:

message, of type DOMString, readonly

The human-readable, localizable text for this compilation message.

Note: The message should follow the best practices for language and direction information. This includes making use of any future standards which may emerge regarding the reporting of string language and direction metadata.

Editorial note: At the time of this writing, no language/direction recommendation is available that provides compatibility and consistency with legacy APIs, but when there is, adopt it formally.

type, of type GPUCompilationMessageType, readonly

The severity level of the message.

If the type is "error", it corresponds to a shader-creation error.

lineNum, of type unsigned long long, readonly

The line number in the shader code the message corresponds to. Value is one-based, such that a lineNum of 1 indicates the first line of the shader code. Lines are delimited by line breaks.

If the message corresponds to a substring this points to the line on which the substring begins. Must be 0 if the message does not correspond to any specific point in the shader code.

linePos, of type unsigned long long, readonly

The offset, in UTF-16 code units, from the beginning of line lineNum of the shader code to the point or beginning of the substring that the message corresponds to. Value is one-based, such that a linePos of 1 indicates the first code unit of the line.

If message corresponds to a substring this points to the first UTF-16 code unit of the substring. Must be 0 if the message does not correspond to any specific point in the shader code.

offset, of type unsigned long long, readonly

The offset from the beginning of the shader code in UTF-16 code units to the point or beginning of the substring that message corresponds to. Must reference the same position as lineNum and linePos. Must be 0 if the message does not correspond to any specific point in the shader code.

length, of type unsigned long long, readonly

The number of UTF-16 code units in the substring that message corresponds to. If the message does not correspond with a substring then length must be 0.

Note: GPUCompilationMessage.lineNum and GPUCompilationMessage.linePos are one-based since the most common use for them is expected to be printing human readable messages that can be correlated with the line and column numbers shown in many text editors.

Note: GPUCompilationMessage.offset and GPUCompilationMessage.length are appropriate to pass to substr() in order to retrieve the substring of the shader code the message corresponds to.

getCompilationInfo()

Returns any messages generated during the GPUShaderModule’s compilation.

The locations, order, and contents of messages are implementation-defined In particular, messages may not be ordered by lineNum.

Called on: GPUShaderModule this

Returns: Promise<GPUCompilationInfo>

Content timeline steps:

  1. Let contentTimeline be the current Content timeline.

  2. Let promise be a new promise.

  3. Issue the synchronization steps on the Device timeline of this.

  4. Return promise.

Device timeline synchronization steps:
  1. Let event occur upon the (successful or unsuccessful) completion of shader module creation for this.

  2. Listen for timeline event event on this.[[device]], handled by the subsequent steps on contentTimeline.

Content timeline steps:
  1. Let info be a new GPUCompilationInfo.

  2. Let messages be a list of any errors, warnings, or informational messages generated during shader module creation for this, or the empty list [] if the device was lost.

  3. For each message in messages:

    1. Let m be a new GPUCompilationMessage.

    2. Set m.message to be the text of message.

    3. If message is a shader-creation error:

      Set m.type to "error"

      If message is a warning:

      Set m.type to "warning"

      Otherwise:

      Set m.type to "info"

    4. If message is associated with a specific substring or position within the shader code:
      1. Set m.lineNum to the one-based number of the first line that the message refers to.

      2. Set m.linePos to the one-based number of the first UTF-16 code units on m.lineNum that the message refers to, or 1 if the message refers to the entire line.

      3. Set m.offset to the number of UTF-16 code units from the beginning of the shader to beginning of the substring or position that message refers to.

      4. Set m.length the length of the substring in UTF-16 code units that message refers to, or 0 if message refers to a position

      Otherwise:
      1. Set m.lineNum to 0.

      2. Set m.linePos to 0.

      3. Set m.offset to 0.

      4. Set m.length to 0.

    5. Append m to info.messages.

  4. Resolve promise with info.

10. Pipelines

A pipeline, be it GPUComputePipeline or GPURenderPipeline, represents the complete function done by a combination of the GPU hardware, the driver, and the user agent, that process the input data in the shape of bindings and vertex buffers, and produces some output, like the colors in the output render targets.

Structurally, the pipeline consists of a sequence of programmable stages (shaders) and fixed-function states, such as the blending modes.

Note: Internally, depending on the target platform, the driver may convert some of the fixed-function states into shader code, and link it together with the shaders provided by the user. This linking is one of the reason the object is created as a whole.

This combination state is created as a single object (a GPUComputePipeline or GPURenderPipeline) and switched using one command (GPUComputePassEncoder.setPipeline() or GPURenderCommandsMixin.setPipeline() respectively).

There are two ways to create pipelines:

immediate pipeline creation

createComputePipeline() and createRenderPipeline() return a pipeline object which can be used immediately in a pass encoder.

When this fails, the pipeline object will be invalid and the call will generate either a validation error or an internal error.

Note: A handle object is returned immediately, but actual pipeline creation is not synchronous. If pipeline creation takes a long time, this can incur a stall in the device timeline at some point between the creation call and execution of the submit() in which it is first used. The point is unspecified, but most likely to be one of: at creation, at the first usage of the pipeline in setPipeline(), at the corresponding finish() of that GPUCommandEncoder or GPURenderBundleEncoder, or at submit() of that GPUCommandBuffer.

async pipeline creation

createComputePipelineAsync() and createRenderPipelineAsync() return a Promise which resolves to a pipeline object when creation of the pipeline has completed.

When this fails, the Promise rejects with a GPUPipelineError.

GPUPipelineError describes a pipeline creation failure.

[Exposed=(Window, Worker), SecureContext, Serializable]
interface GPUPipelineError : DOMException {
    constructor(optional DOMString message = "", GPUPipelineErrorInit options);
    readonly attribute GPUPipelineErrorReason reason;
};

dictionary GPUPipelineErrorInit {
    required GPUPipelineErrorReason reason;
};

enum GPUPipelineErrorReason {
    "validation",
    "internal",
};

GPUPipelineError constructor:

constructor()
Arguments:
Arguments for the GPUPipelineError.constructor() method.
Parameter Type Nullable Optional Description
message DOMString Error message of the base DOMException.
options GPUPipelineErrorInit Options specific to GPUPipelineError.

Content timeline steps:

  1. Set this.name to "GPUPipelineError".

  2. Set this.message to message.

  3. Set this.reason to options.reason.

GPUPipelineError has the following attributes:

reason, of type GPUPipelineErrorReason, readonly

A read-only slot-backed attribute exposing the type of error encountered in pipeline creation as a GPUPipelineErrorReason:

GPUPipelineError objects are serializable objects.

Their serialization steps, given value and serialized, are:
  1. Run the DOMException serialization steps given value and serialized.

Their deserialization steps, given value and serialized, are:
  1. Run the DOMException deserialization steps given value and serialized.

10.1. Base pipelines

enum GPUAutoLayoutMode {
    "auto",
};

dictionary GPUPipelineDescriptorBase
         : GPUObjectDescriptorBase {
    required (GPUPipelineLayout or GPUAutoLayoutMode) layout;
};
layout, of type (GPUPipelineLayout or GPUAutoLayoutMode)

The GPUPipelineLayout for this pipeline, or "auto" to generate the pipeline layout automatically.

Note: If "auto" is used the pipeline cannot share GPUBindGroups with any other pipelines.

interface mixin GPUPipelineBase {
    [NewObject] GPUBindGroupLayout getBindGroupLayout(unsigned long index);
};

GPUPipelineBase has the following device timeline properties:

[[layout]], of type GPUPipelineLayout

The definition of the layout of resources which can be used with this.

GPUPipelineBase has the following methods:

getBindGroupLayout(index)

Gets a GPUBindGroupLayout that is compatible with the GPUPipelineBase’s GPUBindGroupLayout at index.

Called on: GPUPipelineBase this

Arguments:

Arguments for the GPUPipelineBase.getBindGroupLayout(index) method.
Parameter Type Nullable Optional Description
index unsigned long Index into the pipeline layout’s [[bindGroupLayouts]] sequence.

Returns: GPUBindGroupLayout

Content timeline steps:

  1. Let layout be a new GPUBindGroupLayout object.

  2. Issue the initialization steps on the Device timeline of this.

  3. Return layout.

Device timeline initialization steps:
  1. Let limits be this.[[device]].[[limits]].

  2. If any of the following conditions are unsatisfied generate a validation error, invalidate layout and return.

  3. Initialize layout so it is a copy of this.[[layout]].[[bindGroupLayouts]][index].

    Note: GPUBindGroupLayout is only ever used by-value, not by-reference, so this is equivalent to returning the same internal object with a new WebGPU interface. A new GPUBindGroupLayout WebGPU interface is returned each time to avoid a round-trip between the Content timeline and the Device timeline.

10.1.1. Default pipeline layout

A GPUPipelineBase object that was created with a layout set to "auto" has a default layout created and used instead.

Note: Default layouts are provided as a convenience for simple pipelines, but use of explicit layouts is recommended in most cases. Bind groups created from default layouts cannot be used with other pipelines, and the structure of the default layout may change when altering shaders, causing unexpected bind group creation errors.

To create a default pipeline layout for GPUPipelineBase pipeline, run the following device timeline steps:

  1. Let groupCount be 0.

  2. Let groupDescs be a sequence of device.[[limits]].maxBindGroups new GPUBindGroupLayoutDescriptor objects.

  3. For each groupDesc in groupDescs:

    1. Set groupDesc.entries to an empty sequence.

  4. For each GPUProgrammableStage stageDesc in the descriptor used to create pipeline:

    1. Let shaderStage be the GPUShaderStageFlags for the shader stage at which stageDesc is used in pipeline.

    2. Let entryPoint be get the entry point(shaderStage, stageDesc). Assert entryPoint is not null.

    3. For each resource resource statically used by entryPoint:

      1. Let group be resource’s "group" decoration.

      2. Let binding be resource’s "binding" decoration.

      3. Let entry be a new GPUBindGroupLayoutEntry.

      4. Set entry.binding to binding.

      5. Set entry.visibility to shaderStage.

      6. If resource is for a sampler binding:

        1. Let samplerLayout be a new GPUSamplerBindingLayout.

        2. Set entry.sampler to samplerLayout.

      7. If resource is for a comparison sampler binding:

        1. Let samplerLayout be a new GPUSamplerBindingLayout.

        2. Set samplerLayout.type to "comparison".

        3. Set entry.sampler to samplerLayout.

      8. If resource is for a buffer binding:

        1. Let bufferLayout be a new GPUBufferBindingLayout.

        2. Set bufferLayout.minBindingSize to resource’s minimum buffer binding size.

        3. If resource is for a read-only storage buffer:

          1. Set bufferLayout.type to "read-only-storage".

        4. If resource is for a storage buffer:

          1. Set bufferLayout.type to "storage".

        5. Set entry.buffer to bufferLayout.

      9. If resource is for a sampled texture binding:

        1. Let textureLayout be a new GPUTextureBindingLayout.

        2. If resource is a depth texture binding:

          Else if the sampled type of resource is:

          f32 and there exists a static use of resource by stageDesc in a texture builtin function call that also uses a sampler

          Set textureLayout.sampleType to "float"

          f32 otherwise

          Set textureLayout.sampleType to "unfilterable-float"

          i32

          Set textureLayout.sampleType to "sint"

          u32

          Set textureLayout.sampleType to "uint"

        3. Set textureLayout.viewDimension to resource’s dimension.

        4. If resource is for a multisampled texture:

          1. Set textureLayout.multisampled to true.

        5. Set entry.texture to textureLayout.

      10. If resource is for a storage texture binding:

        1. Let storageTextureLayout be a new GPUStorageTextureBindingLayout.

        2. Set storageTextureLayout.format to resource’s format.

        3. Set storageTextureLayout.viewDimension to resource’s dimension.

        4. If the access mode is:

          read

          Set textureLayout.access to "read-only".

          write

          Set textureLayout.access to "write-only".

          read_write

          Set textureLayout.access to "read-write".

        5. Set entry.storageTexture to storageTextureLayout.

      11. Set groupCount to max(groupCount, group + 1).

      12. If groupDescs[group] has an entry previousEntry with binding equal to binding:

        1. If entry has different visibility than previousEntry:

          1. Add the bits set in entry.visibility into previousEntry.visibility

        2. If resource is for a buffer binding and entry has greater buffer.minBindingSize than previousEntry:

          1. Set previousEntry.buffer.minBindingSize to entry.buffer.minBindingSize.

        3. If resource is a sampled texture binding and entry has different texture.sampleType than previousEntry and both entry and previousEntry have texture.sampleType of either "float" or "unfilterable-float":

          1. Set previousEntry.texture.sampleType to "float".

        4. If any other property is unequal between entry and previousEntry:

          1. Return null (which will cause the creation of the pipeline to fail).

        5. If resource is a storage texture binding, entry.storageTexture.access is "read-write", previousEntry.storageTexture.access is "write-only", and previousEntry.storageTexture.format is compatible with STORAGE_BINDING and "read-write" according to the § 26.1.1 Plain color formats table:

          1. Set previousEntry.storageTexture.access to "read-write".

      13. Else

        1. Append entry to groupDescs[group].

  5. Let groupLayouts be a new list.

  6. For each i from 0 to groupCount - 1, inclusive:

    1. Let groupDesc be groupDescs[i].

    2. Let bindGroupLayout be the result of calling device.createBindGroupLayout()(groupDesc).

    3. Set bindGroupLayout.[[exclusivePipeline]] to pipeline.

    4. Append bindGroupLayout to groupLayouts.

  7. Let desc be a new GPUPipelineLayoutDescriptor.

  8. Set desc.bindGroupLayouts to groupLayouts.

  9. Return device.createPipelineLayout()(desc).

10.1.2. GPUProgrammableStage

A GPUProgrammableStage describes the entry point in the user-provided GPUShaderModule that controls one of the programmable stages of a pipeline. Entry point names follow the rules defined in WGSL identifier comparison.

dictionary GPUProgrammableStage {
    required GPUShaderModule module;
    USVString entryPoint;
    record<USVString, GPUPipelineConstantValue> constants = {};
};

typedef double GPUPipelineConstantValue; // May represent WGSL's bool, f32, i32, u32, and f16 if enabled.

GPUProgrammableStage has the following members:

module, of type GPUShaderModule

The GPUShaderModule containing the code that this programmable stage will execute.

entryPoint, of type USVString

The name of the function in module that this stage will use to perform its work.

NOTE: Since the entryPoint dictionary member is not required, methods which consume a GPUProgrammableStage must use the "get the entry point" algorithm to determine which entry point it refers to.

constants, of type record<USVString, GPUPipelineConstantValue>, defaulting to {}

Specifies the values of pipeline-overridable constants in the shader module module.

Each such pipeline-overridable constant is uniquely identified by a single pipeline-overridable constant identifier string, representing the pipeline constant ID of the constant if its declaration specifies one, and otherwise the constant’s identifier name.

The key of each key-value pair must equal the identifier string of one such constant, with the comparison performed according to the rules for WGSL identifier comparison. When the pipeline is executed, that constant will have the specified value.

Values are specified as GPUPipelineConstantValue, which is a double. They are converted to WGSL type of the pipeline-overridable constant (bool/i32/u32/f32/f16). If conversion fails, a validation error is generated.

Pipeline-overridable constants defined in WGSL:
@id(0)      override has_point_light: bool = true;  // Algorithmic control.
@id(1200)   override specular_param: f32 = 2.3;     // Numeric control.
@id(1300)   override gain: f32;                     // Must be overridden.
            override width: f32 = 0.0;              // Specifed at the API level
                                                    //   using the name "width".
            override depth: f32;                    // Specifed at the API level
                                                    //   using the name "depth".
                                                    //   Must be overridden.
            override height = 2 * depth;            // The default value
                                                    // (if not set at the API level),
                                                    // depends on another
                                                    // overridable constant.

Corresponding JavaScript code, providing only the overrides which are required (have no defaults):

{
    // ...
    constants: {
        1300: 2.0,  // "gain"
        depth: -1,  // "depth"
    }
}

Corresponding JavaScript code, overriding all constants:

{
    // ...
    constants: {
        0: false,   // "has_point_light"
        1200: 3.0,  // "specular_param"
        1300: 2.0,  // "gain"
        width: 20,  // "width"
        depth: -1,  // "depth"
        height: 15, // "height"
    }
}
To get the entry point(GPUShaderStage stage, GPUProgrammableStage descriptor), run the following device timeline steps:
  1. If descriptor.entryPoint is provided:

    1. If descriptor.module contains an entry point whose name equals descriptor.entryPoint, and whose shader stage equals stage, return that entry point.

      Otherwise, return null.

    Otherwise:

    1. If there is exactly one entry point in descriptor.module whose shader stage equals stage, return that entry point.

      Otherwise, return null.

validating GPUProgrammableStage(stage, descriptor, layout, device)

Arguments:

All of the requirements in the following steps must be met. If any are unmet, return false; otherwise, return true.

  1. descriptor.module must be valid to use with device.

  2. Let entryPoint be get the entry point(stage, descriptor).

  3. entryPoint must not be null.

  4. For each binding that is statically used by entryPoint:

  5. For each texture builtin function call in any of the functions in the shader stage rooted at entryPoint, if it uses a textureBinding of sampled texture or depth texture type together with a samplerBinding of sampler type (excluding sampler_comparison):

    1. Let texture be the GPUBindGroupLayoutEntry corresponding to textureBinding.

    2. Let sampler be the GPUBindGroupLayoutEntry corresponding to samplerBinding.

    3. If sampler.type is "filtering", then texture.sampleType must be "float".

    Note: "comparison" samplers can also only be used with "depth" textures, because they are the only texture type that can be bound to WGSL texture_depth_* bindings.

  6. For each keyvalue in descriptor.constants:

    1. key must equal the pipeline-overridable constant identifier string of some pipeline-overridable constant defined in the shader module descriptor.module by the rules defined in WGSL identifier comparison. The pipeline-overridable constant is not required to be statically used by entryPoint. Let the type of that constant be T.

    2. Converting the IDL value value to WGSL type T must not throw a TypeError.

  7. For each pipeline-overridable constant identifier string key which is statically used by entryPoint:

  8. Pipeline-creation program errors must not result from the rules of the [WGSL] specification.

validating shader binding(variable, layout)

Arguments:

Let bindGroup be the bind group index, and bindIndex be the binding index, of the shader binding declaration variable.

Return true if all of the following conditions are satisfied:

The minimum buffer binding size for a buffer binding variable var is computed as follows:
  1. Let T be the store type of var.

  2. If T is a runtime-sized array, or contains a runtime-sized array, replace that array<E> with array<E, 1>.

    Note: This ensures there’s always enough memory for one element, which allows array indices to be clamped to the length of the array resulting in an in-memory access.

  3. Return SizeOf(T).

Note: Enforcing this lower bound ensures reads and writes via the buffer variable only access memory locations within the bound region of the buffer.

A resource binding, pipeline-overridable constant, shader stage input, or shader stage output is considered to be statically used by an entry point if it is present in the interface of the shader stage for that entry point.

10.2. GPUComputePipeline

A GPUComputePipeline is a kind of pipeline that controls the compute shader stage, and can be used in GPUComputePassEncoder.

Compute inputs and outputs are all contained in the bindings, according to the given GPUPipelineLayout. The outputs correspond to buffer bindings with a type of "storage" and storageTexture bindings with a type of "write-only" or "read-write".

Stages of a compute pipeline:

  1. Compute shader

[Exposed=(Window, Worker), SecureContext]
interface GPUComputePipeline {
};
GPUComputePipeline includes GPUObjectBase;
GPUComputePipeline includes GPUPipelineBase;

10.2.1. Compute Pipeline Creation

A GPUComputePipelineDescriptor describes a compute pipeline. See § 23.1 Computing for additional details.

dictionary GPUComputePipelineDescriptor
         : GPUPipelineDescriptorBase {
    required GPUProgrammableStage compute;
};

GPUComputePipelineDescriptor has the following members:

compute, of type GPUProgrammableStage

Describes the compute shader entry point of the pipeline.

createComputePipeline(descriptor)

Creates a GPUComputePipeline using immediate pipeline creation.

Called on: GPUDevice this.

Arguments:

Arguments for the GPUDevice.createComputePipeline(descriptor) method.
Parameter Type Nullable Optional Description
descriptor GPUComputePipelineDescriptor Description of the GPUComputePipeline to create.

Returns: GPUComputePipeline

Content timeline steps:

  1. Let pipeline be ! create a new WebGPU object(this, GPUComputePipeline, descriptor).

  2. Issue the initialization steps on the Device timeline of this.

  3. Return pipeline.

Device timeline initialization steps:
  1. Let layout be a new default pipeline layout for pipeline if descriptor.layout is "auto", and descriptor.layout otherwise.

  2. All of the requirements in the following steps must be met. If any are unmet, generate a validation error, invalidate pipeline and return.

    1. layout must be valid to use with this.

    2. validating GPUProgrammableStage(COMPUTE, descriptor.compute, layout, this) must succeed.

    3. Let entryPoint be get the entry point(COMPUTE, descriptor.compute).

      Assert entryPoint is not null.

    4. Let workgroupStorageUsed be the sum of roundUp(16, SizeOf(T)) over each type T of all variables with address space "workgroup" statically used by entryPoint.

      workgroupStorageUsed must be ≤ device.limits.maxComputeWorkgroupStorageSize.

    5. entryPoint must use ≤ device.limits.maxComputeInvocationsPerWorkgroup per workgroup.

    6. Each component of entryPoint’s workgroup_size attribute must be ≤ the corresponding component in [device.limits.maxComputeWorkgroupSizeX, device.limits.maxComputeWorkgroupSizeY, device.limits.maxComputeWorkgroupSizeZ].

  3. If any pipeline-creation uncategorized errors result from the implementation of pipeline creation, generate an internal error, invalidate pipeline and return.

    Note: Even if the implementation detected uncategorized errors in shader module creation, the error is surfaced here.

  4. Set pipeline.[[layout]] to layout.

createComputePipelineAsync(descriptor)

Creates a GPUComputePipeline using async pipeline creation. The returned Promise resolves when the created pipeline is ready to be used without additional delay.

If pipeline creation fails, the returned Promise rejects with an GPUPipelineError. (A GPUError is not dispatched to the device.)

Note: Use of this method is preferred whenever possible, as it prevents blocking the queue timeline work on pipeline compilation.

Called on: GPUDevice this.

Arguments:

Arguments for the GPUDevice.createComputePipelineAsync(descriptor) method.
Parameter Type Nullable Optional Description
descriptor GPUComputePipelineDescriptor Description of the GPUComputePipeline to create.

Returns: Promise<GPUComputePipeline>

Content timeline steps:

  1. Let contentTimeline be the current Content timeline.

  2. Let promise be a new promise.

  3. Issue the initialization steps on the Device timeline of this.

  4. Return promise.

Device timeline initialization steps:
  1. Let pipeline be a new GPUComputePipeline created as if this.createComputePipeline() was called with descriptor, except capturing any errors as error, rather than dispatching them to the device.

  2. Let event occur upon the (successful or unsuccessful) completion of pipeline creation for pipeline.

  3. Listen for timeline event event on this.[[device]], handled by the subsequent steps on the device timeline of this.

Device timeline steps:
  1. If pipeline is valid or this is lost:

    1. Issue the following steps on contentTimeline:

      Content timeline steps:
      1. Resolve promise with pipeline.

    2. Return.

    Note: No errors are generated from a device which is lost. See § 22 Errors & Debugging.

  2. If pipeline is invalid and error is an internal error, issue the following steps on contentTimeline, and return.

  3. If pipeline is invalid and error is a validation error, issue the following steps on contentTimeline, and return.

Creating a simple GPUComputePipeline:
const computePipeline = gpuDevice.createComputePipeline({
    layout: pipelineLayout,
    compute: {
        module: computeShaderModule,
        entryPoint: 'computeMain',
    }
});

10.3. GPURenderPipeline

A GPURenderPipeline is a kind of pipeline that controls the vertex and fragment shader stages, and can be used in GPURenderPassEncoder as well as GPURenderBundleEncoder.

Render pipeline inputs are:

Render pipeline outputs are:

A render pipeline is comprised of the following render stages:

  1. Vertex fetch, controlled by GPUVertexState.buffers

  2. Vertex shader, controlled by GPUVertexState

  3. Primitive assembly, controlled by GPUPrimitiveState

  4. Rasterization, controlled by GPUPrimitiveState, GPUDepthStencilState, and GPUMultisampleState

  5. Fragment shader, controlled by GPUFragmentState

  6. Stencil test and operation, controlled by GPUDepthStencilState

  7. Depth test and write, controlled by GPUDepthStencilState

  8. Output merging, controlled by GPUFragmentState.targets

[Exposed=(Window, Worker), SecureContext]
interface GPURenderPipeline {
};
GPURenderPipeline includes GPUObjectBase;
GPURenderPipeline includes GPUPipelineBase;

GPURenderPipeline has the following device timeline properties:

[[descriptor]], of type GPURenderPipelineDescriptor, readonly

The GPURenderPipelineDescriptor describing this pipeline.

All optional fields of GPURenderPipelineDescriptor are defined.

[[writesDepth]], of type boolean, readonly

True if the pipeline writes to the depth component of the depth/stencil attachment

[[writesStencil]], of type boolean, readonly

True if the pipeline writes to the stencil component of the depth/stencil attachment

10.3.1. Render Pipeline Creation

A GPURenderPipelineDescriptor describes a render pipeline by configuring each of the render stages. See § 23.2 Rendering for additional details.

dictionary GPURenderPipelineDescriptor
         : GPUPipelineDescriptorBase {
    required GPUVertexState vertex;
    GPUPrimitiveState primitive = {};
    GPUDepthStencilState depthStencil;
    GPUMultisampleState multisample = {};
    GPUFragmentState fragment;
};

GPURenderPipelineDescriptor has the following members:

vertex, of type GPUVertexState

Describes the vertex shader entry point of the pipeline and its input buffer layouts.

primitive, of type GPUPrimitiveState, defaulting to {}

Describes the primitive-related properties of the pipeline.

depthStencil, of type GPUDepthStencilState

Describes the optional depth-stencil properties, including the testing, operations, and bias.

multisample, of type GPUMultisampleState, defaulting to {}

Describes the multi-sampling properties of the pipeline.

fragment, of type GPUFragmentState

Describes the fragment shader entry point of the pipeline and its output colors. If not provided, the § 23.2.8 No Color Output mode is enabled.

createRenderPipeline(descriptor)

Creates a GPURenderPipeline using immediate pipeline creation.

Called on: GPUDevice this.

Arguments:

Arguments for the GPUDevice.createRenderPipeline(descriptor) method.
Parameter Type Nullable Optional Description
descriptor GPURenderPipelineDescriptor Description of the GPURenderPipeline to create.

Returns: GPURenderPipeline

Content timeline steps:

  1. If descriptor.fragment is provided:

    1. For each non-null colorState of descriptor.fragment.targets:

      1. ? Validate texture format required features of colorState.format with this.[[device]].

  2. If descriptor.depthStencil is provided:

    1. ? Validate texture format required features of descriptor.depthStencil.format with this.[[device]].

  3. Let pipeline be ! create a new WebGPU object(this, GPURenderPipeline, descriptor).

  4. Issue the initialization steps on the Device timeline of this.

  5. Return pipeline.

Device timeline initialization steps:
  1. Let layout be a new default pipeline layout for pipeline if descriptor.layout is "auto", and descriptor.layout otherwise.

  2. All of the requirements in the following steps must be met. If any are unmet, generate a validation error, invalidate pipeline, and return.

    1. layout must be valid to use with this.

    2. validating GPURenderPipelineDescriptor(descriptor, layout, this) must succeed.

    3. Let vertexBufferCount be the index of the last non-null entry in descriptor.vertex.buffers, plus 1; or 0 if there are none.

    4. layout.[[bindGroupLayouts]].size + vertexBufferCount must be ≤ this.[[device]].[[limits]].maxBindGroupsPlusVertexBuffers.

  3. If any pipeline-creation uncategorized errors result from the implementation of pipeline creation, generate an internal error, invalidate pipeline and return.

    Note: Even if the implementation detected uncategorized errors in shader module creation, the error is surfaced here.

  4. Set pipeline.[[descriptor]] to descriptor.

  5. Set pipeline.[[writesDepth]] to false.

  6. Set pipeline.[[writesStencil]] to false.

  7. Let depthStencil be descriptor.depthStencil.

  8. If depthStencil is not null:

    1. If depthStencil.depthWriteEnabled is provided:

      1. Set pipeline.[[writesDepth]] to depthStencil.depthWriteEnabled.

    2. If depthStencil.stencilWriteMask is not 0:

      1. Let stencilFront be depthStencil.stencilFront.

      2. Let stencilBack be depthStencil.stencilBack.

      3. Let cullMode be descriptor.primitive.cullMode.

      4. If cullMode is not "front", and any of stencilFront.passOp, stencilFront.depthFailOp, or stencilFront.failOp is not "keep":

        1. Set pipeline.[[writesStencil]] to true.

      5. If cullMode is not "back", and any of stencilBack.passOp, stencilBack.depthFailOp, or stencilBack.failOp is not "keep":

        1. Set pipeline.[[writesStencil]] to true.

  9. Set pipeline.[[layout]] to layout.

createRenderPipelineAsync(descriptor)

Creates a GPURenderPipeline using async pipeline creation. The returned Promise resolves when the created pipeline is ready to be used without additional delay.

If pipeline creation fails, the returned Promise rejects with an GPUPipelineError. (A GPUError is not dispatched to the device.)

Note: Use of this method is preferred whenever possible, as it prevents blocking the queue timeline work on pipeline compilation.

Called on: GPUDevice this.

Arguments:

Arguments for the GPUDevice.createRenderPipelineAsync(descriptor) method.
Parameter Type Nullable Optional Description
descriptor GPURenderPipelineDescriptor Description of the GPURenderPipeline to create.

Returns: Promise<GPURenderPipeline>

Content timeline steps:

  1. Let contentTimeline be the current Content timeline.

  2. Let promise be a new promise.

  3. Issue the initialization steps on the Device timeline of this.

  4. Return promise.

Device timeline initialization steps:
  1. Let pipeline be a new GPURenderPipeline created as if this.createRenderPipeline() was called with descriptor, except capturing any errors as error, rather than dispatching them to the device.

  2. Let event occur upon the (successful or unsuccessful) completion of pipeline creation for pipeline.

  3. Listen for timeline event event on this.[[device]], handled by the subsequent steps on the device timeline of this.

Device timeline steps:
  1. If pipeline is valid or this is lost:

    1. Issue the following steps on contentTimeline:

      Content timeline steps:
      1. Resolve promise with pipeline.

    2. Return.

    Note: No errors are generated from a device which is lost. See § 22 Errors & Debugging.

  2. If pipeline is invalid and error is an internal error, issue the following steps on contentTimeline, and return.

  3. If pipeline is invalid and error is a validation error, issue the following steps on contentTimeline, and return.

validating GPURenderPipelineDescriptor(descriptor, layout, device)

Arguments:

Device timeline steps:

  1. Return true if all of the following conditions are satisfied:

validating inter-stage interfaces(device, descriptor)

Arguments:

Returns: boolean

Device timeline steps:

  1. Let maxVertexShaderOutputVariables be device.limits.maxInterStageShaderVariables.

  2. Let maxVertexShaderOutputLocation be device.limits.maxInterStageShaderVariables - 1.

  3. If descriptor.primitive.topology is "point-list":

    1. Decrement maxVertexShaderOutputVariables by 1.

  4. If clip_distances is declared in the output of descriptor.vertex:

    1. Let clipDistancesSize be the array size of clip_distances.

    2. Decrement maxVertexShaderOutputVariables by ceil(clipDistancesSize / 4).

    3. Decrement maxVertexShaderOutputLocation by ceil(clipDistancesSize / 4).

  5. Return false if any of the following requirements are unmet:

    • There must be no more than maxVertexShaderOutputVariables user-defined outputs for descriptor.vertex.

    • The location of each user-defined output of descriptor.vertex must be ≤ maxVertexShaderOutputLocation.

  6. If descriptor.fragment is provided:

    1. Let maxFragmentShaderInputVariables be device.limits.maxInterStageShaderVariables.

    2. If any of the front_facing, sample_index, or sample_mask builtins are an input of descriptor.fragment:

      1. Decrement maxFragmentShaderInputVariables by 1.

    3. Return false if any of the following requirements are unmet:

      • For each user-defined input of descriptor.fragment there must be a user-defined output of descriptor.vertex that location, type, and interpolation of the input.

        Note: Vertex-only pipelines can have user-defined outputs in the vertex stage; their values will be discarded.

      • There must be no more than maxFragmentShaderInputVariables user-defined inputs for descriptor.fragment.

    4. Assert that the location of each user-defined input of descriptor.fragment is less than device.limits.maxInterStageShaderVariables. (This follows from the above rules.)

  7. Return true.

Creating a simple GPURenderPipeline:
const renderPipeline = gpuDevice.createRenderPipeline({
    layout: pipelineLayout,
    vertex: {
        module: shaderModule,
        entryPoint: 'vertexMain'
    },
    fragment: {
        module: shaderModule,
        entryPoint: 'fragmentMain',
        targets: [{
            format: 'bgra8unorm',
        }],
    }
});

10.3.2. Primitive State

dictionary GPUPrimitiveState {
    GPUPrimitiveTopology topology = "triangle-list";
    GPUIndexFormat stripIndexFormat;
    GPUFrontFace frontFace = "ccw";
    GPUCullMode cullMode = "none";

    // Requires "depth-clip-control" feature.
    boolean unclippedDepth = false;
};

GPUPrimitiveState has the following members, which describe how a GPURenderPipeline constructs and rasterizes primitives from its vertex inputs:

topology, of type GPUPrimitiveTopology, defaulting to "triangle-list"

The type of primitive to be constructed from the vertex inputs.

stripIndexFormat, of type GPUIndexFormat

For pipelines with strip topologies ("line-strip" or "triangle-strip"), this determines the index buffer format and primitive restart value ("uint16"/0xFFFF or "uint32"/0xFFFFFFFF). It is not allowed on pipelines with non-strip topologies.

Note: Some implementations require knowledge of the primitive restart value to compile pipeline state objects.

To use a strip-topology pipeline with an indexed draw call (drawIndexed() or drawIndexedIndirect()), this must be set, and it must match the index buffer format used with the draw call (set in setIndexBuffer()).

See § 23.2.3 Primitive Assembly for additional details.

frontFace, of type GPUFrontFace, defaulting to "ccw"

Defines which polygons are considered front-facing.

cullMode, of type GPUCullMode, defaulting to "none"

Defines which polygon orientation will be culled, if any.

unclippedDepth, of type boolean, defaulting to false

If true, indicates that depth clipping is disabled.

Requires the "depth-clip-control" feature to be enabled.

validating GPUPrimitiveState(descriptor, device) Arguments:

Device timeline steps:

  1. Return true if all of the following conditions are satisfied:

enum GPUPrimitiveTopology {
    "point-list",
    "line-list",
    "line-strip",
    "triangle-list",
    "triangle-strip",
};

GPUPrimitiveTopology defines the primitive type draw calls made with a GPURenderPipeline will use. See § 23.2.5 Rasterization for additional details:

"point-list"

Each vertex defines a point primitive.

"line-list"

Each consecutive pair of two vertices defines a line primitive.

"line-strip"

Each vertex after the first defines a line primitive between it and the previous vertex.

"triangle-list"

Each consecutive triplet of three vertices defines a triangle primitive.

"triangle-strip"

Each vertex after the first two defines a triangle primitive between it and the previous two vertices.

enum GPUFrontFace {
    "ccw",
    "cw",
};

GPUFrontFace defines which polygons are considered front-facing by a GPURenderPipeline. See § 23.2.5.4 Polygon Rasterization for additional details:

"ccw"

Polygons with vertices whose framebuffer coordinates are given in counter-clockwise order are considered front-facing.

"cw"

Polygons with vertices whose framebuffer coordinates are given in clockwise order are considered front-facing.

enum GPUCullMode {
    "none",
    "front",
    "back",
};

GPUPrimitiveTopology defines which polygons will be culled by draw calls made with a GPURenderPipeline. See § 23.2.5.4 Polygon Rasterization for additional details:

"none"

No polygons are discarded.

"front"

Front-facing polygons are discarded.

"back"

Back-facing polygons are discarded.

Note: GPUFrontFace and GPUCullMode have no effect on "point-list", "line-list", or "line-strip" topologies.

10.3.3. Multisample State

dictionary GPUMultisampleState {
    GPUSize32 count = 1;
    GPUSampleMask mask = 0xFFFFFFFF;
    boolean alphaToCoverageEnabled = false;
};

GPUMultisampleState has the following members, which describe how a GPURenderPipeline interacts with a render pass’s multisampled attachments.

count, of type GPUSize32, defaulting to 1

Number of samples per pixel. This GPURenderPipeline will be compatible only with attachment textures (colorAttachments and depthStencilAttachment) with matching sampleCounts.

mask, of type GPUSampleMask, defaulting to 0xFFFFFFFF

Mask determining which samples are written to.

alphaToCoverageEnabled, of type boolean, defaulting to false

When true indicates that a fragment’s alpha channel should be used to generate a sample coverage mask.

validating GPUMultisampleState(descriptor) Arguments:

Device timeline steps:

  1. Return true if all of the following conditions are satisfied:

10.3.4. Fragment State

dictionary GPUFragmentState
         : GPUProgrammableStage {
    required sequence<GPUColorTargetState?> targets;
};
targets, of type sequence<GPUColorTargetState?>

A list of GPUColorTargetState defining the formats and behaviors of the color targets this pipeline writes to.

validating GPUFragmentState(device, descriptor, layout)

Arguments:

Device timeline steps:

  1. Return true if all of the following requirements are met:

Validating GPUFragmentState’s color attachment bytes per sample(device, targets)

Arguments:

Device timeline steps:

  1. Let formats be an empty list<GPUTextureFormat?>

  2. For each target in targets:

    1. If target is undefined, continue.

    2. Append target.format to formats.

  3. Calculating color attachment bytes per sample(formats) must be ≤ device.[[limits]].maxColorAttachmentBytesPerSample.

Note: The fragment shader may output more values than what the pipeline uses. If that is the case the values are ignored.

GPUBlendComponent component is a valid GPUBlendComponent with logical device device if it meets
the following requirements:

10.3.5. Color Target State

dictionary GPUColorTargetState {
    required GPUTextureFormat format;

    GPUBlendState blend;
    GPUColorWriteFlags writeMask = 0xF;  // GPUColorWrite.ALL
};
format, of type GPUTextureFormat

The GPUTextureFormat of this color target. The pipeline will only be compatible with GPURenderPassEncoders which use a GPUTextureView of this format in the corresponding color attachment.

blend, of type GPUBlendState

The blending behavior for this color target. If left undefined, disables blending for this color target.

writeMask, of type GPUColorWriteFlags, defaulting to 0xF

Bitmask controlling which channels are are written to when drawing to this color target.

dictionary GPUBlendState {
    required GPUBlendComponent color;
    required GPUBlendComponent alpha;
};
color, of type GPUBlendComponent

Defines the blending behavior of the corresponding render target for color channels.

alpha, of type GPUBlendComponent

Defines the blending behavior of the corresponding render target for the alpha channel.

typedef [EnforceRange] unsigned long GPUColorWriteFlags;
[Exposed=(Window, Worker), SecureContext]
namespace GPUColorWrite {
    const GPUFlagsConstant RED   = 0x1;
    const GPUFlagsConstant GREEN = 0x2;
    const GPUFlagsConstant BLUE  = 0x4;
    const GPUFlagsConstant ALPHA = 0x8;
    const GPUFlagsConstant ALL   = 0xF;
};
10.3.5.1. Blend State
dictionary GPUBlendComponent {
    GPUBlendOperation operation = "add";
    GPUBlendFactor srcFactor = "one";
    GPUBlendFactor dstFactor = "zero";
};

GPUBlendComponent has the following members, which describe how the color or alpha components of a fragment are blended:

operation, of type GPUBlendOperation, defaulting to "add"

Defines the GPUBlendOperation used to calculate the values written to the target attachment components.

srcFactor, of type GPUBlendFactor, defaulting to "one"

Defines the GPUBlendFactor operation to be performed on values from the fragment shader.

dstFactor, of type GPUBlendFactor, defaulting to "zero"

Defines the GPUBlendFactor operation to be performed on values from the target attachment.

The following tables use this notation to describe color components for a given fragment location:

RGBAsrc Color output by the fragment shader for the color attachment. If the shader doesn’t return an alpha channel, src-alpha blend factors cannot be used.
RGBAsrc1 Color output by the fragment shader for the color attachment with "@blend_src" attribute equal to 1. If the shader doesn’t return an alpha channel, src1-alpha blend factors cannot be used.
RGBAdst Color currently in the color attachment. Missing green/blue/alpha channels default to 0, 0, 1, respectively.
RGBAconst The current [[blendConstant]].
RGBAsrcFactor The source blend factor components, as defined by srcFactor.
RGBAdstFactor The destination blend factor components, as defined by dstFactor.
enum GPUBlendFactor {
    "zero",
    "one",
    "src",
    "one-minus-src",
    "src-alpha",
    "one-minus-src-alpha",
    "dst",
    "one-minus-dst",
    "dst-alpha",
    "one-minus-dst-alpha",
    "src-alpha-saturated",
    "constant",
    "one-minus-constant",
    "src1",
    "one-minus-src1",
    "src1-alpha",
    "one-minus-src1-alpha",
};

GPUBlendFactor defines how either a source or destination blend factors is calculated:

GPUBlendFactor Blend factor RGBA components Feature
"zero" (0, 0, 0, 0)
"one" (1, 1, 1, 1)
"src" (Rsrc, Gsrc, Bsrc, Asrc)
"one-minus-src" (1 - Rsrc, 1 - Gsrc, 1 - Bsrc, 1 - Asrc)
"src-alpha" (Asrc, Asrc, Asrc, Asrc)
"one-minus-src-alpha" (1 - Asrc, 1 - Asrc, 1 - Asrc, 1 - Asrc)
"dst" (Rdst, Gdst, Bdst, Adst)
"one-minus-dst" (1 - Rdst, 1 - Gdst, 1 - Bdst, 1 - Adst)
"dst-alpha" (Adst, Adst, Adst, Adst)
"one-minus-dst-alpha" (1 - Adst, 1 - Adst, 1 - Adst, 1 - Adst)
"src-alpha-saturated" (min(Asrc, 1 - Adst), min(Asrc, 1 - Adst), min(Asrc, 1 - Adst), 1)
"constant" (Rconst, Gconst, Bconst, Aconst)
"one-minus-constant" (1 - Rconst, 1 - Gconst, 1 - Bconst, 1 - Aconst)
"src1" (Rsrc1, Gsrc1, Bsrc1, Asrc1) dual-source-blending
"one-minus-src1" (1 - Rsrc1, 1 - Gsrc1, 1 - Bsrc1, 1 - Asrc1)
"src1-alpha" (Asrc1, Asrc1, Asrc1, Asrc1)
"one-minus-src1-alpha" (1 - Asrc1, 1 - Asrc1, 1 - Asrc1, 1 - Asrc1)
enum GPUBlendOperation {
    "add",
    "subtract",
    "reverse-subtract",
    "min",
    "max",
};

GPUBlendOperation defines the algorithm used to combine source and destination blend factors:

GPUBlendOperation RGBA Components
"add" RGBAsrc × RGBAsrcFactor + RGBAdst × RGBAdstFactor
"subtract" RGBAsrc × RGBAsrcFactor - RGBAdst × RGBAdstFactor
"reverse-subtract" RGBAdst × RGBAdstFactor - RGBAsrc × RGBAsrcFactor
"min" min(RGBAsrc, RGBAdst)
"max" max(RGBAsrc, RGBAdst)

10.3.6. Depth/Stencil State

dictionary GPUDepthStencilState {
    required GPUTextureFormat format;

    boolean depthWriteEnabled;
    GPUCompareFunction depthCompare;

    GPUStencilFaceState stencilFront = {};
    GPUStencilFaceState stencilBack = {};

    GPUStencilValue stencilReadMask = 0xFFFFFFFF;
    GPUStencilValue stencilWriteMask = 0xFFFFFFFF;

    GPUDepthBias depthBias = 0;
    float depthBiasSlopeScale = 0;
    float depthBiasClamp = 0;
};

GPUDepthStencilState has the following members, which describe how a GPURenderPipeline will affect a render pass’s depthStencilAttachment:

format, of type GPUTextureFormat

The format of depthStencilAttachment this GPURenderPipeline will be compatible with.

depthWriteEnabled, of type boolean

Indicates if this GPURenderPipeline can modify depthStencilAttachment depth values.

depthCompare, of type GPUCompareFunction

The comparison operation used to test fragment depths against depthStencilAttachment depth values.

stencilFront, of type GPUStencilFaceState, defaulting to {}

Defines how stencil comparisons and operations are performed for front-facing primitives.

stencilBack, of type GPUStencilFaceState, defaulting to {}

Defines how stencil comparisons and operations are performed for back-facing primitives.

stencilReadMask, of type GPUStencilValue, defaulting to 0xFFFFFFFF

Bitmask controlling which depthStencilAttachment stencil value bits are read when performing stencil comparison tests.

stencilWriteMask, of type GPUStencilValue, defaulting to 0xFFFFFFFF

Bitmask controlling which depthStencilAttachment stencil value bits are written to when performing stencil operations.

depthBias, of type GPUDepthBias, defaulting to 0

Constant depth bias added to each triangle fragment. See biased fragment depth for details.

depthBiasSlopeScale, of type float, defaulting to 0

Depth bias that scales with the triangle fragment’s slope. See biased fragment depth for details.

depthBiasClamp, of type float, defaulting to 0

The maximum depth bias of a triangle fragment. See biased fragment depth for details.

Note: depthBias, depthBiasSlopeScale, and depthBiasClamp have no effect on "point-list", "line-list", and "line-strip" primitives, and must be 0.

The biased fragment depth for a fragment being written to depthStencilAttachment attachment when drawing using GPUDepthStencilState state is calculated by running the following queue timeline steps:
  1. Let format be attachment.view.format.

  2. Let r be the minimum positive representable value > 0 in the format converted to a 32-bit float.

  3. Let maxDepthSlope be the maximum of the horizontal and vertical slopes of the fragment’s depth value.

  4. If format is a unorm format:

    1. Let bias be (float)state.depthBias * r + state.depthBiasSlopeScale * maxDepthSlope.

  5. Otherwise, if format is a float format:

    1. Let bias be (float)state.depthBias * 2^(exp(max depth in primitive) - r) + state.depthBiasSlopeScale * maxDepthSlope.

  6. If state.depthBiasClamp > 0:

    1. Set bias to min(state.depthBiasClamp, bias).

  7. Otherwise if state.depthBiasClamp < 0:

    1. Set bias to max(state.depthBiasClamp, bias).

  8. If state.depthBias0 or state.depthBiasSlopeScale0:

    1. Set the fragment depth value to fragment depth value + bias

validating GPUDepthStencilState(descriptor, topology)

Arguments:

Device timeline steps:

  1. Return true if, and only if, all of the following conditions are satisfied:

dictionary GPUStencilFaceState {
    GPUCompareFunction compare = "always";
    GPUStencilOperation failOp = "keep";
    GPUStencilOperation depthFailOp = "keep";
    GPUStencilOperation passOp = "keep";
};

GPUStencilFaceState has the following members, which describe how stencil comparisons and operations are performed:

compare, of type GPUCompareFunction, defaulting to "always"

The GPUCompareFunction used when testing the [[stencilReference]] value against the fragment’s depthStencilAttachment stencil values.

failOp, of type GPUStencilOperation, defaulting to "keep"

The GPUStencilOperation performed if the fragment stencil comparison test described by compare fails.

depthFailOp, of type GPUStencilOperation, defaulting to "keep"

The GPUStencilOperation performed if the fragment depth comparison described by depthCompare fails.

passOp, of type GPUStencilOperation, defaulting to "keep"

The GPUStencilOperation performed if the fragment stencil comparison test described by compare passes.

enum GPUStencilOperation {
    "keep",
    "zero",
    "replace",
    "invert",
    "increment-clamp",
    "decrement-clamp",
    "increment-wrap",
    "decrement-wrap",
};

GPUStencilOperation defines the following operations:

"keep"

Keep the current stencil value.

"zero"

Set the stencil value to 0.

"replace"

Set the stencil value to [[stencilReference]].

"invert"

Bitwise-invert the current stencil value.

"increment-clamp"

Increments the current stencil value, clamping to the maximum representable value of the depthStencilAttachment’s stencil aspect.

"decrement-clamp"

Decrement the current stencil value, clamping to 0.

"increment-wrap"

Increments the current stencil value, wrapping to zero if the value exceeds the maximum representable value of the depthStencilAttachment’s stencil aspect.

"decrement-wrap"

Decrement the current stencil value, wrapping to the maximum representable value of the depthStencilAttachment’s stencil aspect if the value goes below 0.

10.3.7. Vertex State

enum GPUIndexFormat {
    "uint16",
    "uint32",
};

The index format determines both the data type of index values in a buffer and, when used with strip primitive topologies ("line-strip" or "triangle-strip") also specifies the primitive restart value. The primitive restart value indicates which index value indicates that a new primitive should be started rather than continuing to construct the triangle strip with the prior indexed vertices.

GPUPrimitiveStates that specify a strip primitive topology must specify a stripIndexFormat if they are used for indexed draws so that the primitive restart value that will be used is known at pipeline creation time. GPUPrimitiveStates that specify a list primitive topology will use the index format passed to setIndexBuffer() when doing indexed rendering.

Index format Byte size Primitive restart value
"uint16" 2 0xFFFF
"uint32" 4 0xFFFFFFFF
10.3.7.1. Vertex Formats

The GPUVertexFormat of a vertex attribute indicates how data from a vertex buffer will be interpreted and exposed to the shader. The name of the format specifies the order of components, bits per component, and vertex data type for the component.

Each vertex data type can map to any WGSL scalar type of the same base type, regardless of the bits per component:

Vertex format prefix Vertex data type Compatible WGSL types
uint unsigned int u32
sint signed int i32
unorm unsigned normalized f16, f32
snorm signed normalized
float floating point

The multi-component formats specify the number of components after "x". Mismatches in the number of components between the vertex format and shader type are allowed, with components being either dropped or filled with default values to compensate.

A vertex attribute with a format of "unorm8x2" and byte values [0x7F, 0xFF] can be accessed in the shader with the following types:
Shader type Shader value
f16 0.5h
f32 0.5f
vec2<f16> vec2(0.5h, 1.0h)
vec2<f32> vec2(0.5f, 1.0f)
vec3<f16> vec2(0.5h, 1.0h, 0.0h)
vec3<f32> vec2(0.5f, 1.0f, 0.0f)
vec4<f16> vec2(0.5h, 1.0h, 0.0h, 1.0h)
vec4<f32> vec2(0.5f, 1.0f, 0.0f, 1.0f)

See § 23.2.2 Vertex Processing for additional information about how vertex formats are exposed in the shader.

enum GPUVertexFormat {
    "uint8",
    "uint8x2",
    "uint8x4",
    "sint8",
    "sint8x2",
    "sint8x4",
    "unorm8",
    "unorm8x2",
    "unorm8x4",
    "snorm8",
    "snorm8x2",
    "snorm8x4",
    "uint16",
    "uint16x2",
    "uint16x4",
    "sint16",
    "sint16x2",
    "sint16x4",
    "unorm16",
    "unorm16x2",
    "unorm16x4",
    "snorm16",
    "snorm16x2",
    "snorm16x4",
    "float16",
    "float16x2",
    "float16x4",
    "float32",
    "float32x2",
    "float32x3",
    "float32x4",
    "uint32",
    "uint32x2",
    "uint32x3",
    "uint32x4",
    "sint32",
    "sint32x2",
    "sint32x3",
    "sint32x4",
    "unorm10-10-10-2",
    "unorm8x4-bgra",
};
Vertex format Data type Components byteSize Example WGSL type
"uint8" unsigned int 1 1 u32
"uint8x2" unsigned int 2 2 vec2<u32>
"uint8x4" unsigned int 4 4 vec4<u32>
"sint8" signed int 1 1 i32
"sint8x2" signed int 2 2 vec2<i32>
"sint8x4" signed int 4 4 vec4<i32>
"unorm8" unsigned normalized 1 1 f32
"unorm8x2" unsigned normalized 2 2 vec2<f32>
"unorm8x4" unsigned normalized 4 4 vec4<f32>
"snorm8" signed normalized 1 1 f32
"snorm8x2" signed normalized 2 2 vec2<f32>
"snorm8x4" signed normalized 4 4 vec4<f32>
"uint16" unsigned int 1 2 u32
"uint16x2" unsigned int 2 4 vec2<u32>
"uint16x4" unsigned int 4 8 vec4<u32>
"sint16" signed int 1 2 i32
"sint16x2" signed int 2 4 vec2<i32>
"sint16x4" signed int 4 8 vec4<i32>
"unorm16" unsigned normalized 1 2 f32
"unorm16x2" unsigned normalized 2 4 vec2<f32>
"unorm16x4" unsigned normalized 4 8 vec4<f32>
"snorm16" signed normalized 1 2 f32
"snorm16x2" signed normalized 2 4 vec2<f32>
"snorm16x4" signed normalized 4 8 vec4<f32>
"float16" float 1 2 f32
"float16x2" float 2 4 vec2<f16>
"float16x4" float 4 8 vec4<f16>
"float32" float 1 4 f32
"float32x2" float 2 8 vec2<f32>
"float32x3" float 3 12 vec3<f32>
"float32x4" float 4 16 vec4<f32>
"uint32" unsigned int 1 4 u32
"uint32x2" unsigned int 2 8 vec2<u32>
"uint32x3" unsigned int 3 12 vec3<u32>
"uint32x4" unsigned int 4 16 vec4<u32>
"sint32" signed int 1 4 i32
"sint32x2" signed int 2 8 vec2<i32>
"sint32x3" signed int 3 12 vec3<i32>
"sint32x4" signed int 4 16 vec4<i32>
"unorm10-10-10-2" unsigned normalized 4 4 vec4<f32>
"unorm8x4-bgra" unsigned normalized 4 4 vec4<f32>
enum GPUVertexStepMode {
    "vertex",
    "instance",
};

The step mode configures how an address for vertex buffer data is computed, based on the current vertex or instance index:

"vertex"

The address is advanced by arrayStride for each vertex, and reset between instances.

"instance"

The address is advanced by arrayStride for each instance.

dictionary GPUVertexState
         : GPUProgrammableStage {
    sequence<GPUVertexBufferLayout?> buffers = [];
};
buffers, of type sequence<GPUVertexBufferLayout?>, defaulting to []

A list of GPUVertexBufferLayouts, each defining the layout of vertex attribute data in a vertex buffer used by this pipeline.

A vertex buffer is, conceptually, a view into buffer memory as an array of structures. arrayStride is the stride, in bytes, between elements of that array. Each element of a vertex buffer is like a structure with a memory layout defined by its attributes, which describe the members of the structure.

Each GPUVertexAttribute describes its format and its offset, in bytes, within the structure.

Each attribute appears as a separate input in a vertex shader, each bound by a numeric location, which is specified by shaderLocation. Every location must be unique within the GPUVertexState.

dictionary GPUVertexBufferLayout {
    required GPUSize64 arrayStride;
    GPUVertexStepMode stepMode = "vertex";
    required sequence<GPUVertexAttribute> attributes;
};
arrayStride, of type GPUSize64

The stride, in bytes, between elements of this array.

stepMode, of type GPUVertexStepMode, defaulting to "vertex"

Whether each element of this array represents per-vertex data or per-instance data

attributes, of type sequence<GPUVertexAttribute>

An array defining the layout of the vertex attributes within each element.

dictionary GPUVertexAttribute {
    required GPUVertexFormat format;
    required GPUSize64 offset;

    required GPUIndex32 shaderLocation;
};
format, of type GPUVertexFormat

The GPUVertexFormat of the attribute.

offset, of type GPUSize64

The offset, in bytes, from the beginning of the element to the data for the attribute.

shaderLocation, of type GPUIndex32

The numeric location associated with this attribute, which will correspond with a "@location" attribute declared in the vertex.module.

validating GPUVertexBufferLayout(device, descriptor)

Arguments:

Device timeline steps:

  1. Return true, if and only if, all of the following conditions are satisfied:

validating GPUVertexState(device, descriptor, layout)

Arguments:

Device timeline steps:

  1. Let entryPoint be get the entry point(VERTEX, descriptor).

  2. Assert entryPoint is not null.

  3. All of the requirements in the following steps must be met.

    1. validating GPUProgrammableStage(VERTEX, descriptor, layout, device) must succeed.

    2. descriptor.buffers.size must be ≤ device.[[device]].[[limits]].maxVertexBuffers.

    3. Each vertexBuffer layout descriptor in the list descriptor.buffers must pass validating GPUVertexBufferLayout(device, vertexBuffer).

    4. The sum of vertexBuffer.attributes.size, over every vertexBuffer in descriptor.buffers, must be ≤ device.[[device]].[[limits]].maxVertexAttributes.

    5. For every vertex attribute declaration (at location location with type T) that is statically used by entryPoint, there must be exactly one pair (i, j) for which descriptor.buffers[i]?.attributes[j].shaderLocation == location.

      Let attrib be that GPUVertexAttribute.

    6. T must be compatible with attrib.format’s vertex data type:

      "unorm", "snorm", or "float"

      T must be f32 or vecN<f32>.

      "uint"

      T must be u32 or vecN<u32>.

      "sint"

      T must be i32 or vecN<i32>.

11. Copies

11.1. Buffer Copies

Buffer copy operations operate on raw bytes.

WebGPU provides "buffered" GPUCommandEncoder commands:

and "immediate" GPUQueue operations:

11.2. Texel Copies

Texel copy operations operate on texture/"image" data, rather than bytes.

WebGPU provides "buffered" GPUCommandEncoder commands:

and "immediate" GPUQueue operations:

During a texel copy texels are copied over with an equivalent texel representation. Texel copies only guarantee that valid, normal numeric values in the source have the same numeric value in the destination, and may not preserve the bit-representations of the the following values:

Note: Copies may be performed with WGSL shaders, which means that any of the documented WGSL floating point behaviors may be observed.

The following definitions are used by these methods:

11.2.1. GPUTexelCopyBufferLayout

"GPUTexelCopyBufferLayout" describes the "layout" of texels in a "buffer" of bytes (GPUBuffer or AllowSharedBufferSource) in a "texel copy" operation.

dictionary GPUTexelCopyBufferLayout {
    GPUSize64 offset = 0;
    GPUSize32 bytesPerRow;
    GPUSize32 rowsPerImage;
};

A texel image is comprised of one or more rows of texel blocks, referred to here as texel block rows. Each texel block row of a texel image must contain the same number of texel blocks, and all texel blocks in a texel image are of the same GPUTextureFormat.

A GPUTexelCopyBufferLayout is a layout of texel images within some linear memory. It’s used when copying data between a texture and a GPUBuffer, or when scheduling a write into a texture from the GPUQueue.

Operations that copy between byte arrays and textures always operate on whole texel block. It’s not possible to update only a part of a texel block.

Texel blocks are tightly packed within each texel block row in the linear memory layout of a texel copy, with each subsequent texel block immediately following the previous texel block, with no padding. This includes copies to/from specific aspects of depth-or-stencil format textures: stencil values are tightly packed in an array of bytes; depth values are tightly packed in an array of the appropriate type ("depth16unorm" or "depth32float").

offset, of type GPUSize64, defaulting to 0

The offset, in bytes, from the beginning of the texel data source (such as a GPUTexelCopyBufferInfo.buffer) to the start of the texel data within that source.

bytesPerRow, of type GPUSize32

The stride, in bytes, between the beginning of each texel block row and the subsequent texel block row.

Required if there are multiple texel block rows (i.e. the copy height or depth is more than one block).

rowsPerImage, of type GPUSize32

Number of texel block rows per single texel image of the texture. rowsPerImage × bytesPerRow is the stride, in bytes, between the beginning of each texel image of data and the subsequent texel image.

Required if there are multiple texel images (i.e. the copy depth is more than one).

11.2.2. GPUTexelCopyBufferInfo

"GPUTexelCopyBufferInfo" describes the "info" (GPUBuffer and GPUTexelCopyBufferLayout) about a "buffer" source or destination of a "texel copy" operation. Together with the copySize, it describes the footprint of a region of texels in a GPUBuffer.

dictionary GPUTexelCopyBufferInfo
         : GPUTexelCopyBufferLayout {
    required GPUBuffer buffer;
};
buffer, of type GPUBuffer

A buffer which either contains texel data to be copied or will store the texel data being copied, depending on the method it is being passed to.

validating GPUTexelCopyBufferInfo

Arguments:

Returns: boolean

Device timeline steps:

  1. Return true if and only if all of the following conditions are satisfied:

11.2.3. GPUTexelCopyTextureInfo

"GPUTexelCopyTextureInfo" describes the "info" (GPUTexture, etc.) about a "texture" source or destination of a "texel copy" operation. Together with the copySize, it describes a sub-region of a texture (spanning one or more contiguous texture subresources at the same mip-map level).

dictionary GPUTexelCopyTextureInfo {
    required GPUTexture texture;
    GPUIntegerCoordinate mipLevel = 0;
    GPUOrigin3D origin = {};
    GPUTextureAspect aspect = "all";
};
texture, of type GPUTexture

Texture to copy to/from.

mipLevel, of type GPUIntegerCoordinate, defaulting to 0

Mip-map level of the texture to copy to/from.

origin, of type GPUOrigin3D, defaulting to {}

Defines the origin of the copy - the minimum corner of the texture sub-region to copy to/from. Together with copySize, defines the full copy sub-region.

aspect, of type GPUTextureAspect, defaulting to "all"

Defines which aspects of the texture to copy to/from.

The texture copy sub-region for depth slice or array layer index of GPUTexelCopyTextureInfo copyTexture is determined by running the following steps:
  1. Let texture be copyTexture.texture.

  2. If texture.dimension is:

    1d
    1. Assert index is 0

    2. Let depthSliceOrLayer be texture

    2d

    Let depthSliceOrLayer be array layer index of texture

    3d

    Let depthSliceOrLayer be depth slice index of texture

  3. Let textureMip be mip level copyTexture.mipLevel of depthSliceOrLayer.

  4. Return aspect copyTexture.aspect of textureMip.

The texel block byte offset of data described by GPUTexelCopyBufferLayout bufferLayout corresponding to texel block x, y of depth slice or array layer z of a GPUTexture texture is determined by running the following steps:
  1. Let blockBytes be the texel block copy footprint of texture.format.

  2. Let imageOffset be (z × bufferLayout.rowsPerImage × bufferLayout.bytesPerRow) + bufferLayout.offset.

  3. Let rowOffset be (y × bufferLayout.bytesPerRow) + imageOffset.

  4. Let blockOffset be (x × blockBytes) + rowOffset.

  5. Return blockOffset.

validating GPUTexelCopyTextureInfo(texelCopyTextureInfo, copySize)

Arguments:

Returns: boolean

Device timeline steps:

  1. Let blockWidth be the texel block width of texelCopyTextureInfo.texture.format.

  2. Let blockHeight be the texel block height of texelCopyTextureInfo.texture.format.

  3. Return true if and only if all of the following conditions apply:

validating texture buffer copy(texelCopyTextureInfo, bufferLayout, dataLength, copySize, textureUsage, aligned)

Arguments:

Returns: boolean

Device timeline steps:

  1. Let texture be texelCopyTextureInfo.texture

  2. Let aspectSpecificFormat = texture.format.

  3. Let offsetAlignment = texel block copy footprint of texture.format.

  4. Return true if and only if all of the following conditions apply:

    1. validating GPUTexelCopyTextureInfo(texelCopyTextureInfo, copySize) returns true.

    2. texture.sampleCount is 1.

    3. texture.usage contains textureUsage.

    4. If texture.format is a depth-or-stencil format format:

      1. texelCopyTextureInfo.aspect must refer to a single aspect of texture.format.

      2. If textureUsage is:

        COPY_SRC

        That aspect must be a valid texel copy source according to § 26.1.2 Depth-stencil formats.

        COPY_DST

        That aspect must be a valid texel copy destination according to § 26.1.2 Depth-stencil formats.

      3. Set aspectSpecificFormat to the aspect-specific format according to § 26.1.2 Depth-stencil formats.

      4. Set offsetAlignment to 4.

    5. If aligned is true:

      1. bufferLayout.offset is a multiple of offsetAlignment.

    6. validating linear texture data(bufferLayout, dataLength, aspectSpecificFormat, copySize) succeeds.

11.2.4. GPUCopyExternalImageDestInfo

WebGPU textures hold raw numeric data, and are not tagged with semantic metadata describing colors. However, copyExternalImageToTexture() copies from sources that describe colors.

"GPUCopyExternalImageDestInfo" describes the "info" about the "destination" of a "copyExternalImageToTexture()" operation. It is a GPUTexelCopyTextureInfo which is additionally tagged with color space/encoding and alpha-premultiplication metadata, so that semantic color data may be preserved during copies. This metadata affects only the semantics of the copy operation operation, not the state or semantics of the destination texture object.

dictionary GPUCopyExternalImageDestInfo
         : GPUTexelCopyTextureInfo {
    PredefinedColorSpace colorSpace = "srgb";
    boolean premultipliedAlpha = false;
};
colorSpace, of type PredefinedColorSpace, defaulting to "srgb"

Describes the color space and encoding used to encode data into the destination texture.

This may result in values outside of the range [0, 1] being written to the target texture, if its format can represent them. Otherwise, the results are clamped to the target texture format’s range.

Note: If colorSpace matches the source image, conversion may not be necessary. See § 3.10.2 Color Space Conversion Elision.

premultipliedAlpha, of type boolean, defaulting to false

Describes whether the data written into the texture should have its RGB channels premultiplied by the alpha channel, or not.

If this option is set to true and the source is also premultiplied, the source RGB values must be preserved even if they exceed their corresponding alpha values.

Note: If premultipliedAlpha matches the source image, conversion may not be necessary. See § 3.10.2 Color Space Conversion Elision.

11.2.5. GPUCopyExternalImageSourceInfo

"GPUCopyExternalImageSourceInfo" describes the "info" about the "source" of a "copyExternalImageToTexture()" operation.

typedef (ImageBitmap or
         ImageData or
         HTMLImageElement or
         HTMLVideoElement or
         VideoFrame or
         HTMLCanvasElement or
         OffscreenCanvas) GPUCopyExternalImageSource;

dictionary GPUCopyExternalImageSourceInfo {
    required GPUCopyExternalImageSource source;
    GPUOrigin2D origin = {};
    boolean flipY = false;
};

GPUCopyExternalImageSourceInfo has the following members:

source, of type GPUCopyExternalImageSource

The source of the texel copy. The copy source data is captured at the moment that copyExternalImageToTexture() is issued. Source size is determined as described by the external source dimensions table.

origin, of type GPUOrigin2D, defaulting to {}

Defines the origin of the copy - the minimum (top-left) corner of the source sub-region to copy from. Together with copySize, defines the full copy sub-region.

flipY, of type boolean, defaulting to false

Describes whether the source image is vertically flipped, or not.

If this option is set to true, the copy is flipped vertically: the bottom row of the source region is copied into the first row of the destination region, and so on. The origin option is still relative to the top-left corner of the source image, increasing downward.

When external sources are used when creating or copying to textures, the external source dimensions are defined by the source type, given by this table:

External Source type Dimensions
ImageBitmap ImageBitmap.width, ImageBitmap.height
HTMLImageElement HTMLImageElement.naturalWidth, HTMLImageElement.naturalHeight
HTMLVideoElement intrinsic width of the frame, intrinsic height of the frame
VideoFrame VideoFrame.displayWidth, VideoFrame.displayHeight
ImageData ImageData.width, ImageData.height
HTMLCanvasElement or OffscreenCanvas with CanvasRenderingContext2D or GPUCanvasContext HTMLCanvasElement.width, HTMLCanvasElement.height
HTMLCanvasElement or OffscreenCanvas with WebGLRenderingContextBase WebGLRenderingContextBase.drawingBufferWidth, WebGLRenderingContextBase.drawingBufferHeight
HTMLCanvasElement or OffscreenCanvas with ImageBitmapRenderingContext ImageBitmapRenderingContext’s internal output bitmap ImageBitmap.width, ImageBitmap.height

11.2.6. Subroutines

GPUTexelCopyTextureInfo physical subresource size

Arguments:

Returns: GPUExtent3D

The GPUTexelCopyTextureInfo physical subresource size of texelCopyTextureInfo is calculated as follows:

Its width, height and depthOrArrayLayers are the width, height, and depth, respectively, of the physical miplevel-specific texture extent of texelCopyTextureInfo.texture subresource at mipmap level texelCopyTextureInfo.mipLevel.

validating linear texture data(layout, byteSize, format, copyExtent)

Arguments:

GPUTexelCopyBufferLayout layout

Layout of the linear texture data.

GPUSize64 byteSize

Total size of the linear data, in bytes.

GPUTextureFormat format

Format of the texture.

GPUExtent3D copyExtent

Extent of the texture to copy.

Device timeline steps:

  1. Let:

  2. Fail if the following input validation requirements are not met:

  3. Let:

    Note: These default values have no effect, as they’re always multiplied by 0.

  4. Let requiredBytesInCopy be 0.

  5. If copyExtent.depthOrArrayLayers > 0:

    1. Increment requiredBytesInCopy by bytesPerRow × rowsPerImage × (copyExtent.depthOrArrayLayers − 1).

    2. If heightInBlocks > 0:

      1. Increment requiredBytesInCopy by bytesPerRow × (heightInBlocks − 1) + bytesInLastRow.

  6. Fail if the following condition is not satisfied:

    • The layout fits inside the linear data: layout.offset + requiredBytesInCopybyteSize.

validating texture copy range

Arguments:

GPUTexelCopyTextureInfo texelCopyTextureInfo

The texture subresource being copied into and copy origin.

GPUExtent3D copySize

The size of the texture.

Device timeline steps:

  1. Let blockWidth be the texel block width of texelCopyTextureInfo.texture.format.

  2. Let blockHeight be the texel block height of texelCopyTextureInfo.texture.format.

  3. Let subresourceSize be the GPUTexelCopyTextureInfo physical subresource size of texelCopyTextureInfo.

  4. Return whether all the conditions below are satisfied:

    Note: The texture copy range is validated against the physical (rounded-up) size for compressed formats, allowing copies to access texture blocks which are not fully inside the texture.

Two GPUTextureFormats format1 and format2 are copy-compatible if:
The set of subresources for texture copy(texelCopyTextureInfo, copySize) is the subset of subresources of texture = texelCopyTextureInfo.texture for which each subresource s satisfies the following:

12. Command Buffers

Command buffers are pre-recorded lists of GPU commands (blocks of queue timeline steps) that can be submitted to a GPUQueue for execution. Each GPU command represents a task to be performed on the queue timeline, such as setting state, drawing, copying resources, etc.

A GPUCommandBuffer can only be submitted once, at which point it becomes invalidated. To reuse rendering commands across multiple submissions, use GPURenderBundle.

12.1. GPUCommandBuffer

[Exposed=(Window, Worker), SecureContext]
interface GPUCommandBuffer {
};
GPUCommandBuffer includes GPUObjectBase;

GPUCommandBuffer has the following device timeline properties:

[[command_list]], of type list<GPU command>, readonly

A list of GPU commands to be executed on the Queue timeline when this command buffer is submitted.

[[renderState]], of type RenderState, initially null

The current state used by any render pass commands being executed.

12.1.1. Command Buffer Creation

dictionary GPUCommandBufferDescriptor
         : GPUObjectDescriptorBase {
};

13. Command Encoding

13.1. GPUCommandsMixin

GPUCommandsMixin defines state common to all interfaces which encode commands. It has no methods.

interface mixin GPUCommandsMixin {
};

GPUCommandsMixin has the following device timeline properties:

[[state]], of type encoder state, initially "open"

The current state of the encoder.

[[commands]], of type list<GPU command>, initially []

A list of GPU commands to be executed on the Queue timeline when a GPUCommandBuffer containing these commands is submitted.

The encoder state may be one of the following:

"open"

The encoder is available to encode new commands.

"locked"

The encoder cannot be used, because it is locked by a child encoder: it is a GPUCommandEncoder, and a GPURenderPassEncoder or GPUComputePassEncoder is active. The encoder becomes "open" again when the pass is ended.

Any command issued in this state invalidates the encoder.

"ended"

The encoder has been ended and new commands can no longer be encoded.

Any command issued in this state will generate a validation error.

To Validate the encoder state of GPUCommandsMixin encoder run the
following device timeline steps:
  1. If encoder.[[state]] is:

    "open"

    Return true.

    "locked"

    Invalidate encoder and return false.

    "ended"

    Generate a validation error, and return false.

To Enqueue a command on GPUCommandsMixin encoder which issues the steps of a GPU Command command, run the following device timeline steps:
  1. Append command to encoder.[[commands]].

  2. When command is executed as part of a GPUCommandBuffer:

    1. Issue the steps of command.

13.2. GPUCommandEncoder

[Exposed=(Window, Worker), SecureContext]
interface GPUCommandEncoder {
    GPURenderPassEncoder beginRenderPass(GPURenderPassDescriptor descriptor);
    GPUComputePassEncoder beginComputePass(optional GPUComputePassDescriptor descriptor = {});

    undefined copyBufferToBuffer(
        GPUBuffer source,
        GPUBuffer destination,
        optional GPUSize64 size);
    undefined copyBufferToBuffer(
        GPUBuffer source,
        GPUSize64 sourceOffset,
        GPUBuffer destination,
        GPUSize64 destinationOffset,
        optional GPUSize64 size);

    undefined copyBufferToTexture(
        GPUTexelCopyBufferInfo source,
        GPUTexelCopyTextureInfo destination,
        GPUExtent3D copySize);

    undefined copyTextureToBuffer(
        GPUTexelCopyTextureInfo source,
        GPUTexelCopyBufferInfo destination,
        GPUExtent3D copySize);

    undefined copyTextureToTexture(
        GPUTexelCopyTextureInfo source,
        GPUTexelCopyTextureInfo destination,
        GPUExtent3D copySize);

    undefined clearBuffer(
        GPUBuffer buffer,
        optional GPUSize64 offset = 0,
        optional GPUSize64 size);

    undefined resolveQuerySet(
        GPUQuerySet querySet,
        GPUSize32 firstQuery,
        GPUSize32 queryCount,
        GPUBuffer destination,
        GPUSize64 destinationOffset);

    GPUCommandBuffer finish(optional GPUCommandBufferDescriptor descriptor = {});
};
GPUCommandEncoder includes GPUObjectBase;
GPUCommandEncoder includes GPUCommandsMixin;
GPUCommandEncoder includes GPUDebugCommandsMixin;

13.2.1. Command Encoder Creation

dictionary GPUCommandEncoderDescriptor
         : GPUObjectDescriptorBase {
};
createCommandEncoder(descriptor)

Creates a GPUCommandEncoder.

Called on: GPUDevice this.

Arguments:

Arguments for the GPUDevice.createCommandEncoder(descriptor) method.
Parameter Type Nullable Optional Description
descriptor GPUCommandEncoderDescriptor Description of the GPUCommandEncoder to create.

Returns: GPUCommandEncoder

Content timeline steps:

  1. Let e be ! create a new WebGPU object(this, GPUCommandEncoder, descriptor).

  2. Issue the initialization steps on the Device timeline of this.

  3. Return e.

Device timeline initialization steps:
  1. If any of the following conditions are unsatisfied generate a validation error, invalidate e and return.

    • this must not be lost.

Creating a GPUCommandEncoder, encoding a command to clear a buffer, finishing the encoder to get a GPUCommandBuffer, then submitting it to the GPUQueue.
const commandEncoder = gpuDevice.createCommandEncoder();
commandEncoder.clearBuffer(buffer);
const commandBuffer = commandEncoder.finish();
gpuDevice.queue.submit([commandBuffer]);

13.3. Pass Encoding

beginRenderPass(descriptor)

Begins encoding a render pass described by descriptor.

Called on: GPUCommandEncoder this.

Arguments:

Arguments for the GPUCommandEncoder.beginRenderPass(descriptor) method.
Parameter Type Nullable Optional Description
descriptor GPURenderPassDescriptor Description of the GPURenderPassEncoder to create.

Returns: GPURenderPassEncoder

Content timeline steps:

  1. For each non-null colorAttachment in descriptor.colorAttachments:

    1. If colorAttachment.clearValue is provided:

      1. ? validate GPUColor shape(colorAttachment.clearValue).

  2. Let pass be a new GPURenderPassEncoder object.

  3. Issue the initialization steps on the Device timeline of this.

  4. Return pass.

Device timeline initialization steps:
  1. Validate the encoder state of this. If it returns false, invalidate pass and return.

  2. Set this.[[state]] to "locked".

  3. Let attachmentRegions be a list of [texture subresource, depthSlice?] pairs, initially empty. Each pair describes the region of the texture to be rendered to, which includes a single depth slice for "3d" textures only.

  4. For each non-null colorAttachment in descriptor.colorAttachments:

    1. Add [colorAttachment.view, colorAttachment.depthSlice ?? null] to attachmentRegions.

    2. If colorAttachment.resolveTarget is not null:

      1. Add [colorAttachment.resolveTarget, undefined] to attachmentRegions.

  5. If any of the following requirements are unmet, invalidate pass and return.

    • descriptor must meet the Valid Usage rules given device this.[[device]].

    • The set of texture regions in attachmentRegions must be pairwise disjoint. That is, no two texture regions may overlap.

  6. Add each texture subresource in attachmentRegions to pass.[[usage scope]] with usage attachment.

  7. Let depthStencilAttachment be descriptor.depthStencilAttachment.

  8. If depthStencilAttachment is not null:

    1. Let depthStencilView be depthStencilAttachment.view.

    2. Add the depth subresource of depthStencilView, if any, to pass.[[usage scope]] with usage attachment-read if depthStencilAttachment.depthReadOnly is true, or attachment otherwise.

    3. Add the stencil subresource of depthStencilView, if any, to pass.[[usage scope]] with usage attachment-read if depthStencilAttachment.stencilReadOnly is true, or attachment otherwise.

    4. Set pass.[[depthReadOnly]] to depthStencilAttachment.depthReadOnly.

    5. Set pass.[[stencilReadOnly]] to depthStencilAttachment.stencilReadOnly.

  9. Set pass.[[layout]] to derive render targets layout from pass(descriptor).

  10. If descriptor.timestampWrites is provided:

    1. Let timestampWrites be descriptor.timestampWrites.

    2. If timestampWrites.beginningOfPassWriteIndex is provided, append a GPU command to this.[[commands]] with the following steps:

      1. Before the pass commands begin executing, write the current queue timestamp into index timestampWrites.beginningOfPassWriteIndex of timestampWrites.querySet.

    3. If timestampWrites.endOfPassWriteIndex is provided, set pass.[[endTimestampWrite]] to a GPU command with the following steps:

      1. After the pass commands finish executing, write the current queue timestamp into index timestampWrites.endOfPassWriteIndex of timestampWrites.querySet.

  11. Set pass.[[drawCount]] to 0.

  12. Set pass.[[maxDrawCount]] to descriptor.maxDrawCount.

  13. Set pass.[[maxDrawCount]] to descriptor.maxDrawCount.

  14. Enqueue a command on this which issues the subsequent steps on the Queue timeline when executed.

Queue timeline steps:
  1. Let the [[renderState]] of the currently executing GPUCommandBuffer be a new RenderState.

  2. Set [[renderState]].[[colorAttachments]] to descriptor.colorAttachments.

  3. Set [[renderState]].[[depthStencilAttachment]] to descriptor.depthStencilAttachment.

  4. For each non-null colorAttachment in descriptor.colorAttachments:

    1. Let colorView be colorAttachment.view.

    2. If colorView.[[descriptor]].dimension is:

      "3d"

      Let colorSubregion be colorAttachment.depthSlice of colorView.

      Otherwise

      Let colorSubregion be colorView.

    3. If colorAttachment.loadOp is:

      "load"

      Ensure the contents of colorSubregion are loaded into the framebuffer memory associated with colorSubregion.

      "clear"

      Set every texel of the framebuffer memory associated with colorSubregion to colorAttachment.clearValue.

  5. If depthStencilAttachment is not null:

    1. If depthStencilAttachment.depthLoadOp is:

      Not provided

      Assert that depthStencilAttachment.depthReadOnly is true and ensure the contents of the depth subresource of depthStencilView are loaded into the framebuffer memory associated with depthStencilView.

      "load"

      Ensure the contents of the depth subresource of depthStencilView are loaded into the framebuffer memory associated with depthStencilView.

      "clear"

      Set every texel of the framebuffer memory associated with the depth subresource of depthStencilView to depthStencilAttachment.depthClearValue.

    2. If depthStencilAttachment.stencilLoadOp is:

      Not provided

      Assert that depthStencilAttachment.stencilReadOnly is true and ensure the contents of the stencil subresource of depthStencilView are loaded into the framebuffer memory associated with depthStencilView.

      "load"

      Ensure the contents of the stencil subresource of depthStencilView are loaded into the framebuffer memory associated with depthStencilView.

      "clear"

      Set every texel of the framebuffer memory associated with the stencil subresource depthStencilView to depthStencilAttachment.stencilClearValue.

Note: Read-only depth-stencil attachments are implicitly treated as though the "load" operation was used. Validation that requires the load op to not be provided for read-only attachments is done in GPURenderPassDepthStencilAttachment Valid Usage.

beginComputePass(descriptor)

Begins encoding a compute pass described by descriptor.

Called on: GPUCommandEncoder this.

Arguments:

Arguments for the GPUCommandEncoder.beginComputePass(descriptor) method.
Parameter Type Nullable Optional Description
descriptor GPUComputePassDescriptor

Returns: GPUComputePassEncoder

Content timeline steps:

  1. Let pass be a new GPUComputePassEncoder object.

  2. Issue the initialization steps on the Device timeline of this.

  3. Return pass.

Device timeline initialization steps:
  1. Validate the encoder state of this. If it returns false, invalidate pass and return.

  2. Set this.[[state]] to "locked".

  3. If any of the following requirements are unmet, invalidate pass and return.

  4. If descriptor.timestampWrites is provided:

    1. Let timestampWrites be descriptor.timestampWrites.

    2. If timestampWrites.beginningOfPassWriteIndex is provided, append a GPU command to this.[[commands]] with the following steps:

      1. Before the pass commands begin executing, write the current queue timestamp into index timestampWrites.beginningOfPassWriteIndex of timestampWrites.querySet.

    3. If timestampWrites.endOfPassWriteIndex is provided, set pass.[[endTimestampWrite]] to a GPU command with the following steps:

      1. After the pass commands finish executing, write the current queue timestamp into index timestampWrites.endOfPassWriteIndex of timestampWrites.querySet.

13.4. Buffer Copy Commands

copyBufferToBuffer() has two overloads:

copyBufferToBuffer(source, destination, size)

Shorthand, equivalent to copyBufferToBuffer(source, 0, destination, 0, size).

copyBufferToBuffer(source, sourceOffset, destination, destinationOffset, size)

Encode a command into the GPUCommandEncoder that copies data from a sub-region of a GPUBuffer to a sub-region of another GPUBuffer.

Called on: GPUCommandEncoder this.

Arguments:

Arguments for the GPUCommandEncoder.copyBufferToBuffer(source, sourceOffset, destination, destinationOffset, size) method.
Parameter Type Nullable Optional Description
source GPUBuffer The GPUBuffer to copy from.
sourceOffset GPUSize64 Offset in bytes into source to begin copying from.
destination GPUBuffer The GPUBuffer to copy to.
destinationOffset GPUSize64 Offset in bytes into destination to place the copied data.
size GPUSize64 Bytes to copy.

Returns: undefined

Content timeline steps:

  1. Issue the subsequent steps on the Device timeline of this.[[device]].

Device timeline steps:
  1. Validate the encoder state of this. If it returns false, return.

  2. If size is undefined, set it to source.sizesourceOffset.

  3. If any of the following conditions are unsatisfied, invalidate this and return.

  4. Enqueue a command on this which issues the subsequent steps on the Queue timeline when executed.

Queue timeline steps:
  1. Copy size bytes of source, beginning at sourceOffset, into destination, beginning at destinationOffset.

clearBuffer(buffer, offset, size)

Encode a command into the GPUCommandEncoder that fills a sub-region of a GPUBuffer with zeros.

Called on: GPUCommandEncoder this.

Arguments:

Arguments for the GPUCommandEncoder.clearBuffer(buffer, offset, size) method.
Parameter Type Nullable Optional Description
buffer GPUBuffer The GPUBuffer to clear.
offset GPUSize64 Offset in bytes into buffer where the sub-region to clear begins.
size GPUSize64 Size in bytes of the sub-region to clear. Defaults to the size of the buffer minus offset.

Returns: undefined

Content timeline steps:

  1. Issue the subsequent steps on the Device timeline of this.[[device]].

Device timeline steps:
  1. Validate the encoder state of this. If it returns false, return.

  2. If size is missing, set size to max(0, buffer.size - offset).

  3. If any of the following conditions are unsatisfied, invalidate this and return.

  4. Enqueue a command on this which issues the subsequent steps on the Queue timeline when executed.

Queue timeline steps:
  1. Set size bytes of buffer to 0 starting at offset.

13.5. Texel Copy Commands

copyBufferToTexture(source, destination, copySize)

Encode a command into the GPUCommandEncoder that copies data from a sub-region of a GPUBuffer to a sub-region of one or multiple continuous texture subresources.

Called on: GPUCommandEncoder this.

Arguments:

Arguments for the GPUCommandEncoder.copyBufferToTexture(source, destination, copySize) method.
Parameter Type Nullable Optional Description
source GPUTexelCopyBufferInfo Combined with copySize, defines the region of the source buffer.
destination GPUTexelCopyTextureInfo Combined with copySize, defines the region of the destination texture subresource.
copySize GPUExtent3D

Returns: undefined

Content timeline steps:

  1. ? validate GPUOrigin3D shape(destination.origin).

  2. ? validate GPUExtent3D shape(copySize).

  3. Issue the subsequent steps on the Device timeline of this.[[device]]:

Device timeline steps:
  1. Validate the encoder state of this. If it returns false, return.

  2. Let aligned be true.

  3. Let dataLength be source.buffer.size.

  4. If any of the following conditions are unsatisfied, invalidate this and return.

  5. Enqueue a command on this which issues the subsequent steps on the Queue timeline when executed.

Queue timeline steps:
  1. Let blockWidth be the texel block width of destination.texture.

  2. Let blockHeight be the texel block height of destination.texture.

  3. Let dstOrigin be destination.origin.

  4. Let dstBlockOriginX be (dstOrigin.x ÷ blockWidth).

  5. Let dstBlockOriginY be (dstOrigin.y ÷ blockHeight).

  6. Let blockColumns be (copySize.width ÷ blockWidth).

  7. Let blockRows be (copySize.height ÷ blockHeight).

  8. Assert that dstBlockOriginX, dstBlockOriginY, blockColumns, and blockRows are integers.

  9. For each z in the range [0, copySize.depthOrArrayLayers − 1]:

    1. Let dstSubregion be texture copy sub-region (z + dstOrigin.z) of destination.

    2. For each y in the range [0, blockRows − 1]:

      1. For each x in the range [0, blockColumns − 1]:

        1. Let blockOffset be the texel block byte offset of source for (x, y, z) of destination.texture.

        2. Set texel block (dstBlockOriginX + x, dstBlockOriginY + y) of dstSubregion to be an equivalent texel representation to the texel block described by source.buffer at offset blockOffset.

copyTextureToBuffer(source, destination, copySize)

Encode a command into the GPUCommandEncoder that copies data from a sub-region of one or multiple continuous texture subresources to a sub-region of a GPUBuffer.

Called on: GPUCommandEncoder this.

Arguments:

Arguments for the GPUCommandEncoder.copyTextureToBuffer(source, destination, copySize) method.
Parameter Type Nullable Optional Description
source GPUTexelCopyTextureInfo Combined with copySize, defines the region of the source texture subresources.
destination GPUTexelCopyBufferInfo Combined with copySize, defines the region of the destination buffer.
copySize GPUExtent3D

Returns: undefined

Content timeline steps:

  1. ? validate GPUOrigin3D shape(source.origin).

  2. ? validate GPUExtent3D shape(copySize).

  3. Issue the subsequent steps on the Device timeline of this.[[device]]:

Device timeline steps:
  1. Validate the encoder state of this. If it returns false, return.

  2. Let aligned be true.

  3. Let dataLength be destination.buffer.size.

  4. If any of the following conditions are unsatisfied, invalidate this and return.

  5. Enqueue a command on this which issues the subsequent steps on the Queue timeline when executed.

Queue timeline steps:
  1. Let blockWidth be the texel block width of source.texture.

  2. Let blockHeight be the texel block height of source.texture.

  3. Let srcOrigin be source.origin.

  4. Let srcBlockOriginX be (srcOrigin.x ÷ blockWidth).

  5. Let srcBlockOriginY be (srcOrigin.y ÷ blockHeight).

  6. Let blockColumns be (copySize.width ÷ blockWidth).

  7. Let blockRows be (copySize.height ÷ blockHeight).

  8. Assert that srcBlockOriginX, srcBlockOriginY, blockColumns, and blockRows are integers.

  9. For each z in the range [0, copySize.depthOrArrayLayers − 1]:

    1. Let srcSubregion be texture copy sub-region (z + srcOrigin.z) of source.

    2. For each y in the range [0, blockRows − 1]:

      1. For each x in the range [0, blockColumns − 1]:

        1. Let blockOffset be the texel block byte offset of destination for (x, y, z) of source.texture.

        2. Set destination.buffer at offset blockOffset to be an equivalent texel representation to texel block (srcBlockOriginX + x, srcBlockOriginY + y) of srcSubregion.

copyTextureToTexture(source, destination, copySize)

Encode a command into the GPUCommandEncoder that copies data from a sub-region of one or multiple contiguous texture subresources to another sub-region of one or multiple continuous texture subresources.

Called on: GPUCommandEncoder this.

Arguments:

Arguments for the GPUCommandEncoder.copyTextureToTexture(source, destination, copySize) method.
Parameter Type Nullable Optional Description
source GPUTexelCopyTextureInfo Combined with copySize, defines the region of the source texture subresources.
destination GPUTexelCopyTextureInfo Combined with copySize, defines the region of the destination texture subresources.
copySize GPUExtent3D

Returns: undefined

Content timeline steps:

  1. ? validate GPUOrigin3D shape(source.origin).

  2. ? validate GPUOrigin3D shape(destination.origin).

  3. ? validate GPUExtent3D shape(copySize).

  4. Issue the subsequent steps on the Device timeline of this.[[device]]:

Device timeline steps:
  1. Validate the encoder state of this. If it returns false, return.

  2. If any of the following conditions are unsatisfied, invalidate this and return.

  3. Enqueue a command on this which issues the subsequent steps on the Queue timeline when executed.

Queue timeline steps:
  1. Let blockWidth be the texel block width of source.texture.

  2. Let blockHeight be the texel block height of source.texture.

  3. Let srcOrigin be source.origin.

  4. Let srcBlockOriginX be (srcOrigin.x ÷ blockWidth).

  5. Let srcBlockOriginY be (srcOrigin.y ÷ blockHeight).

  6. Let dstOrigin be destination.origin.

  7. Let dstBlockOriginX be (dstOrigin.x ÷ blockWidth).

  8. Let dstBlockOriginY be (dstOrigin.y ÷ blockHeight).

  9. Let blockColumns be (copySize.width ÷ blockWidth).

  10. Let blockRows be (copySize.height ÷ blockHeight).

  11. Assert that srcBlockOriginX, srcBlockOriginY, dstBlockOriginX, dstBlockOriginY, blockColumns, and blockRows are integers.

  12. For each z in the range [0, copySize.depthOrArrayLayers − 1]:

    1. Let srcSubregion be texture copy sub-region (z + srcOrigin.z) of source.

    2. Let dstSubregion be texture copy sub-region (z + dstOrigin.z) of destination.

    3. For each y in the range [0, blockRows − 1]:

      1. For each x in the range [0, blockColumns − 1]:

        1. Set texel block (dstBlockOriginX + x, dstBlockOriginY + y) of dstSubregion to be an equivalent texel representation to texel block (srcBlockOriginX + x, srcBlockOriginY + y) of srcSubregion.

13.6. Queries

resolveQuerySet(querySet, firstQuery, queryCount, destination, destinationOffset)

Resolves query results from a GPUQuerySet out into a range of a GPUBuffer.

Called on: GPUCommandEncoder this.

Arguments:

Arguments for the GPUCommandEncoder.resolveQuerySet(querySet, firstQuery, queryCount, destination, destinationOffset) method.
Parameter Type Nullable Optional Description
querySet GPUQuerySet
firstQuery GPUSize32
queryCount GPUSize32
destination GPUBuffer
destinationOffset GPUSize64

Returns: undefined

Content timeline steps:

  1. Issue the subsequent steps on the Device timeline of this.[[device]].

Device timeline steps:
  1. Validate the encoder state of this. If it returns false, return.

  2. If any of the following conditions are unsatisfied, invalidate this and return.

    • querySet is valid to use with this.

    • destination is valid to use with this.

    • destination.usage contains QUERY_RESOLVE.

    • firstQuery < the number of queries in querySet.

    • (firstQuery + queryCount) ≤ the number of queries in querySet.

    • destinationOffset is a multiple of 256.

    • destinationOffset + 8 × queryCountdestination.size.

  3. Enqueue a command on this which issues the subsequent steps on the Queue timeline when executed.

Queue timeline steps:
  1. Let queryIndex be firstQuery.

  2. Let offset be destinationOffset.

  3. While queryIndex < firstQuery + queryCount:

    1. Set 8 bytes of destination, beginning at offset, to be the value of querySet at queryIndex.

    2. Set queryIndex to be queryIndex + 1.

    3. Set offset to be offset + 8.

13.7. Finalization

A GPUCommandBuffer containing the commands recorded by the GPUCommandEncoder can be created by calling finish(). Once finish() has been called the command encoder can no longer be used.

finish(descriptor)

Completes recording of the commands sequence and returns a corresponding GPUCommandBuffer.

Called on: GPUCommandEncoder this.

Arguments:

Arguments for the GPUCommandEncoder.finish(descriptor) method.
Parameter Type Nullable Optional Description
descriptor GPUCommandBufferDescriptor

Returns: GPUCommandBuffer

Content timeline steps:

  1. Let commandBuffer be a new GPUCommandBuffer.

  2. Issue the finish steps on the Device timeline of this.[[device]].

  3. Return commandBuffer.

Device timeline finish steps:
  1. Let validationSucceeded be true if all of the following requirements are met, and false otherwise.

  2. Set this.[[state]] to "ended".

  3. If validationSucceeded is false, then:

    1. Generate a validation error.

    2. Return an invalidated GPUCommandBuffer.

  4. Set commandBuffer.[[command_list]] to this.[[commands]].

14. Programmable Passes

interface mixin GPUBindingCommandsMixin {
    undefined setBindGroup(GPUIndex32 index, GPUBindGroup? bindGroup,
        optional sequence<GPUBufferDynamicOffset> dynamicOffsets = []);

    undefined setBindGroup(GPUIndex32 index, GPUBindGroup? bindGroup,
        [AllowShared] Uint32Array dynamicOffsetsData,
        GPUSize64 dynamicOffsetsDataStart,
        GPUSize32 dynamicOffsetsDataLength);
};

GPUBindingCommandsMixin assumes the presence of GPUObjectBase and GPUCommandsMixin members on the same object. It must only be included by interfaces which also include those mixins.

GPUBindingCommandsMixin has the following device timeline properties:

[[bind_groups]], of type ordered map<GPUIndex32, GPUBindGroup>, initially empty

The current GPUBindGroup for each index.

[[dynamic_offsets]], of type ordered map<GPUIndex32, list<GPUBufferDynamicOffset>>, initally empty

The current dynamic offsets for each [[bind_groups]] entry.

14.1. Bind Groups

setBindGroup() has two overloads:

setBindGroup(index, bindGroup, dynamicOffsets)

Sets the current GPUBindGroup for the given index.

Called on: GPUBindingCommandsMixin this.

Arguments:

index, of type GPUIndex32, non-nullable, required

The index to set the bind group at.

bindGroup, of type GPUBindGroup, nullable, required

Bind group to use for subsequent render or compute commands.

dynamicOffsets, of type sequence<GPUBufferDynamicOffset>, non-nullable, defaulting to []

Array containing buffer offsets in bytes for each entry in bindGroup marked as buffer.hasDynamicOffset, ordered by GPUBindGroupLayoutEntry.binding. See note for additional details.

Returns: undefined

Content timeline steps:

  1. Issue the subsequent steps on the Device timeline of this.[[device]].

Device timeline steps:
  1. Validate the encoder state of this. If it returns false, return.

  2. Let dynamicOffsetCount be 0 if bindGroup is null, or bindGroup.[[layout]].[[dynamicOffsetCount]] if not.

  3. If any of the following requirements are unmet, invalidate this and return.

  4. If bindGroup is null:

    1. Remove this.[[bind_groups]][index].

    2. Remove this.[[dynamic_offsets]][index].

    Otherwise:

    1. If any of the following requirements are unmet, invalidate this and return.

    2. Set this.[[bind_groups]][index] to be bindGroup.

    3. Set this.[[dynamic_offsets]][index] to be a copy of dynamicOffsets.

    4. If this is a GPURenderCommandsMixin:

      1. For each bindGroup in this.[[bind_groups]], merge bindGroup.[[usedResources]] into this.[[usage scope]]

setBindGroup(index, bindGroup, dynamicOffsetsData, dynamicOffsetsDataStart, dynamicOffsetsDataLength)

Sets the current GPUBindGroup for the given index, specifying dynamic offsets as a subset of a Uint32Array.

Called on: GPUBindingCommandsMixin this.

Arguments:

Arguments for the GPUBindingCommandsMixin.setBindGroup(index, bindGroup, dynamicOffsetsData, dynamicOffsetsDataStart, dynamicOffsetsDataLength) method.
Parameter Type Nullable Optional Description
index GPUIndex32 The index to set the bind group at.
bindGroup GPUBindGroup? Bind group to use for subsequent render or compute commands.
dynamicOffsetsData Uint32Array Array containing buffer offsets in bytes for each entry in bindGroup marked as buffer.hasDynamicOffset, ordered by GPUBindGroupLayoutEntry.binding. See note for additional details.
dynamicOffsetsDataStart GPUSize64 Offset in elements into dynamicOffsetsData where the buffer offset data begins.
dynamicOffsetsDataLength GPUSize32 Number of buffer offsets to read from dynamicOffsetsData.

Returns: undefined

Content timeline steps:

  1. If any of the following requirements are unmet, throw a RangeError and return.

    • dynamicOffsetsDataStart must be ≥ 0.

    • dynamicOffsetsDataStart + dynamicOffsetsDataLength must be ≤ dynamicOffsetsData.length.

  2. Let dynamicOffsets be a list containing the range, starting at index dynamicOffsetsDataStart, of dynamicOffsetsDataLength elements of a copy of dynamicOffsetsData.

  3. Call this.setBindGroup(index, bindGroup, dynamicOffsets).

NOTE:
Dynamic offset are applied in GPUBindGroupLayoutEntry.binding order.

This means that if dynamic bindings is the list of each GPUBindGroupLayoutEntry in the GPUBindGroupLayout with buffer?.hasDynamicOffset set to true, sorted by GPUBindGroupLayoutEntry.binding, then dynamic offset[i], as supplied to setBindGroup(), will correspond to dynamic bindings[i].

For a GPUBindGroupLayout created with the following call:
// Note the bindings are listed out-of-order in this array, but it
// doesn’t matter because they will be sorted by binding index.
let layout = gpuDevice.createBindGroupLayout({
    entries: [{
        binding: 1,
        buffer: {},
    }, {
        binding: 2,
        buffer: { dynamicOffset: true },
    }, {
        binding: 0,
        buffer: { dynamicOffset: true },
    }]
});

Used by a GPUBindGroup created with the following call:

// Like above, the array order doesn’t matter here.
// It doesn’t even need to match the order used in the layout.
let bindGroup = gpuDevice.createBindGroup({
    layout: layout,
    entries: [{
        binding: 1,
        resource: { buffer: bufferA, offset: 256 },
    }, {
        binding: 2,
        resource: { buffer: bufferB, offset: 512 },
    }, {
        binding: 0,
        resource: { buffer: bufferC },
    }]
});

And bound with the following call:

pass.setBindGroup(0, bindGroup, [1024, 2048]);

The following buffer offsets will be applied:

Binding Buffer Offset
0 bufferC 1024 (Dynamic)
1 bufferA 256 (Static)
2 bufferB 2560 (Static + Dynamic)
To Iterate over each dynamic binding offset in a given GPUBindGroup bindGroup with a given list of steps to be executed for each dynamic offset, run the following device timeline steps:
  1. Let dynamicOffsetIndex be 0.

  2. Let layout be bindGroup.[[layout]].

  3. For each GPUBindGroupEntry entry in bindGroup.[[entries]] ordered in increasing values of entry.binding:

    1. Let bindingDescriptor be the GPUBindGroupLayoutEntry at layout.[[entryMap]][entry.binding]:

    2. If bindingDescriptor.buffer?.hasDynamicOffset is true:

      1. Let bufferBinding be get as buffer binding(entry.resource).

      2. Let bufferLayout be bindingDescriptor.buffer.

      3. Call steps with bufferBinding, bufferLayout, and dynamicOffsetIndex.

      4. Let dynamicOffsetIndex be dynamicOffsetIndex + 1

Validate encoder bind groups(encoder, pipeline)

Arguments:

GPUBindingCommandsMixin encoder

Encoder whose bind groups are being validated.

GPUPipelineBase pipeline

Pipeline to validate encoders bind groups are compatible with.

Device timeline steps:

  1. If any of the following conditions are unsatisfied, return false:

Otherwise return true.

Encoder bind groups alias a writable resource(encoder, pipeline) if any writable buffer binding range overlaps with any other binding range of the same buffer, or any writable texture binding overlaps in texture subresources with any other texture binding (which may use the same or a different GPUTextureView object).

Note: This algorithm limits the use of the usage scope storage exception.

Arguments:

GPUBindingCommandsMixin encoder

Encoder whose bind groups are being validated.

GPUPipelineBase pipeline

Pipeline to validate encoders bind groups are compatible with.

Device timeline steps:

  1. For each stage in [VERTEX, FRAGMENT, COMPUTE]:

    1. Let bufferBindings be a list of (GPUBufferBinding, boolean) pairs, where the latter indicates whether the resource was used as writable.

    2. Let textureViews be a list of (GPUTextureView, boolean) pairs, where the latter indicates whether the resource was used as writable.

    3. For each pair of (GPUIndex32 bindGroupIndex, GPUBindGroupLayout bindGroupLayout) in pipeline.[[layout]].[[bindGroupLayouts]]:

      1. Let bindGroup be encoder.[[bind_groups]][bindGroupIndex].

      2. Let bindGroupLayoutEntries be bindGroupLayout.[[descriptor]].entries.

      3. Let bufferRanges be the bound buffer ranges of bindGroup, given dynamic offsets encoder.[[dynamic_offsets]][bindGroupIndex]

      4. For each (GPUBindGroupLayoutEntry bindGroupLayoutEntry, GPUBufferBinding resource) in bufferRanges, in which bindGroupLayoutEntry.visibility contains stage:

        1. Let resourceWritable be (bindGroupLayoutEntry.buffer.type == "storage").

        2. For each pair (GPUBufferBinding pastResource, boolean pastResourceWritable) in bufferBindings:

          1. If (resourceWritable or pastResourceWritable) is true, and pastResource and resource are buffer-binding-aliasing, return true.

        3. Append (resource, resourceWritable) to bufferBindings.

      5. For each GPUBindGroupLayoutEntry bindGroupLayoutEntry in bindGroupLayoutEntries, and corresponding GPUTextureView resource in bindGroup, in which bindGroupLayoutEntry.visibility contains stage:

        1. If bindGroupLayoutEntry.storageTexture is not provided, continue.

        2. Let resourceWritable be whether bindGroupLayoutEntry.storageTexture.access is a writable access mode.

        3. For each pair (GPUTextureView pastResource, boolean pastResourceWritable) in textureViews,

          1. If (resourceWritable or pastResourceWritable) is true, and pastResource and resource is texture-view-aliasing, return true.

        4. Append (resource, resourceWritable) to textureViews.

  2. Return false.

Note: Implementations are strongly encouraged to optimize this algorithm.

15. Debug Markers

GPUDebugCommandsMixin provides methods to apply debug labels to groups of commands or insert a single label into the command sequence.

Debug groups can be nested to create a hierarchy of labeled commands, and must be well-balanced.

Like object labels, these labels have no required behavior, but may be shown in error messages and browser developer tools, and may be passed to native API backends.

interface mixin GPUDebugCommandsMixin {
    undefined pushDebugGroup(USVString groupLabel);
    undefined popDebugGroup();
    undefined insertDebugMarker(USVString markerLabel);
};

GPUDebugCommandsMixin assumes the presence of GPUObjectBase and GPUCommandsMixin members on the same object. It must only be included by interfaces which also include those mixins.

GPUDebugCommandsMixin has the following device timeline properties:

[[debug_group_stack]], of type stack<USVString>

A stack of active debug group labels.

GPUDebugCommandsMixin has the following methods:

pushDebugGroup(groupLabel)

Begins a labeled debug group containing subsequent commands.

Called on: GPUDebugCommandsMixin this.

Arguments:

Arguments for the GPUDebugCommandsMixin.pushDebugGroup(groupLabel) method.
Parameter Type Nullable Optional Description
groupLabel USVString The label for the command group.

Returns: undefined

Content timeline steps:

  1. Issue the subsequent steps on the Device timeline of this.[[device]].

Device timeline steps:
  1. Validate the encoder state of this. If it returns false, return.

  2. Push groupLabel onto this.[[debug_group_stack]].

popDebugGroup()

Ends the labeled debug group most recently started by pushDebugGroup().

Called on: GPUDebugCommandsMixin this.

Returns: undefined

Content timeline steps:

  1. Issue the subsequent steps on the Device timeline of this.[[device]].

Device timeline steps:
  1. Validate the encoder state of this. If it returns false, return.

  2. If any of the following requirements are unmet, invalidate this and return.

  3. Pop an entry off of this.[[debug_group_stack]].

insertDebugMarker(markerLabel)

Marks a point in a stream of commands with a label.

Called on: GPUDebugCommandsMixin this.

Arguments:

Arguments for the GPUDebugCommandsMixin.insertDebugMarker(markerLabel) method.
Parameter Type Nullable Optional Description
markerLabel USVString The label to insert.

Returns: undefined

Content timeline steps:

  1. Issue the subsequent steps on the Device timeline of this.[[device]].

Device timeline steps:
  1. Validate the encoder state of this. If it returns false, return.

16. Compute Passes

16.1. GPUComputePassEncoder

[Exposed=(Window, Worker), SecureContext]
interface GPUComputePassEncoder {
    undefined setPipeline(GPUComputePipeline pipeline);
    undefined dispatchWorkgroups(GPUSize32 workgroupCountX, optional GPUSize32 workgroupCountY = 1, optional GPUSize32 workgroupCountZ = 1);
    undefined dispatchWorkgroupsIndirect(GPUBuffer indirectBuffer, GPUSize64 indirectOffset);

    undefined end();
};
GPUComputePassEncoder includes GPUObjectBase;
GPUComputePassEncoder includes GPUCommandsMixin;
GPUComputePassEncoder includes GPUDebugCommandsMixin;
GPUComputePassEncoder includes GPUBindingCommandsMixin;

GPUComputePassEncoder has the following device timeline properties:

[[command_encoder]], of type GPUCommandEncoder, readonly

The GPUCommandEncoder that created this compute pass encoder.

[[endTimestampWrite]], of type GPU command?, readonly, defaulting to null

GPU command, if any, writing a timestamp when the pass ends.

[[pipeline]], of type GPUComputePipeline, initially null

The current GPUComputePipeline.

16.1.1. Compute Pass Encoder Creation

dictionary GPUComputePassTimestampWrites {
    required GPUQuerySet querySet;
    GPUSize32 beginningOfPassWriteIndex;
    GPUSize32 endOfPassWriteIndex;
};
querySet, of type GPUQuerySet

The GPUQuerySet, of type "timestamp", that the query results will be written to.

beginningOfPassWriteIndex, of type GPUSize32

If defined, indicates the query index in querySet into which the timestamp at the beginning of the compute pass will be written.

endOfPassWriteIndex, of type GPUSize32

If defined, indicates the query index in querySet into which the timestamp at the end of the compute pass will be written.

Note: Timestamp query values are written in nanoseconds, but how the value is determined is implementation-defined and may not increase monotonically. See § 20.4 Timestamp Query for details.

dictionary GPUComputePassDescriptor
         : GPUObjectDescriptorBase {
    GPUComputePassTimestampWrites timestampWrites;
};
timestampWrites, of type GPUComputePassTimestampWrites

Defines which timestamp values will be written for this pass, and where to write them to.

16.1.2. Dispatch

setPipeline(pipeline)

Sets the current GPUComputePipeline.

Called on: GPUComputePassEncoder this.

Arguments:

Arguments for the GPUComputePassEncoder.setPipeline(pipeline) method.
Parameter Type Nullable Optional Description
pipeline GPUComputePipeline The compute pipeline to use for subsequent dispatch commands.

Returns: undefined

Content timeline steps:

  1. Issue the subsequent steps on the Device timeline of this.[[device]].

Device timeline steps:
  1. Validate the encoder state of this. If it returns false, return.

  2. If any of the following conditions are unsatisfied, invalidate this and return.

  3. Set this.[[pipeline]] to be pipeline.

dispatchWorkgroups(workgroupCountX, workgroupCountY, workgroupCountZ)

Dispatch work to be performed with the current GPUComputePipeline. See § 23.1 Computing for the detailed specification.

Called on: GPUComputePassEncoder this.

Arguments:

Arguments for the GPUComputePassEncoder.dispatchWorkgroups(workgroupCountX, workgroupCountY, workgroupCountZ) method.
Parameter Type Nullable Optional Description
workgroupCountX GPUSize32 X dimension of the grid of workgroups to dispatch.
workgroupCountY GPUSize32 Y dimension of the grid of workgroups to dispatch.
workgroupCountZ GPUSize32 Z dimension of the grid of workgroups to dispatch.
NOTE:
The x, y, and z values passed to dispatchWorkgroups() and dispatchWorkgroupsIndirect() are the number of workgroups to dispatch for each dimension, not the number of shader invocations to perform across each dimension. This matches the behavior of modern native GPU APIs, but differs from the behavior of OpenCL.

This means that if a GPUShaderModule defines an entry point with @workgroup_size(4, 4), and work is dispatched to it with the call computePass.dispatchWorkgroups(8, 8); the entry point will be invoked 1024 times total: Dispatching a 4x4 workgroup 8 times along both the X and Y axes. (4*4*8*8=1024)

Returns: undefined

Content timeline steps:

  1. Issue the subsequent steps on the Device timeline of this.[[device]].

Device timeline steps:
  1. Validate the encoder state of this. If it returns false, return.

  2. Let usageScope be an empty usage scope.

  3. For each bindGroup in this.[[bind_groups]], merge bindGroup.[[usedResources]] into this.[[usage scope]]

  4. If any of the following conditions are unsatisfied, invalidate this and return.

  5. Let bindingState be a snapshot of this’s current state.

  6. Enqueue a command on this which issues the subsequent steps on the Queue timeline.

Queue timeline steps:
  1. Execute a grid of workgroups with dimensions [workgroupCountX, workgroupCountY, workgroupCountZ] with bindingState.[[pipeline]] using bindingState.[[bind_groups]].

dispatchWorkgroupsIndirect(indirectBuffer, indirectOffset)

Dispatch work to be performed with the current GPUComputePipeline using parameters read from a GPUBuffer. See § 23.1 Computing for the detailed specification.

The indirect dispatch parameters encoded in the buffer must be a tightly packed block of three 32-bit unsigned integer values (12 bytes total), given in the same order as the arguments for dispatchWorkgroups(). For example:

let dispatchIndirectParameters = new Uint32Array(3);
dispatchIndirectParameters[0] = workgroupCountX;
dispatchIndirectParameters[1] = workgroupCountY;
dispatchIndirectParameters[2] = workgroupCountZ;
Called on: GPUComputePassEncoder this.

Arguments:

Arguments for the GPUComputePassEncoder.dispatchWorkgroupsIndirect(indirectBuffer, indirectOffset) method.
Parameter Type Nullable Optional Description
indirectBuffer GPUBuffer Buffer containing the indirect dispatch parameters.
indirectOffset GPUSize64 Offset in bytes into indirectBuffer where the dispatch data begins.

Returns: undefined

Content timeline steps:

  1. Issue the subsequent steps on the Device timeline of this.[[device]].

Device timeline steps:
  1. Validate the encoder state of this. If it returns false, return.

  2. Let usageScope be an empty usage scope.

  3. For each bindGroup in this.[[bind_groups]], merge bindGroup.[[usedResources]] into this.[[usage scope]]

  4. Add indirectBuffer to usageScope with usage input.

  5. If any of the following conditions are unsatisfied, invalidate this and return.

  6. Let bindingState be a snapshot of this’s current state.

  7. Enqueue a command on this which issues the subsequent steps on the Queue timeline.

Queue timeline steps:
  1. Let workgroupCountX be an unsigned 32-bit integer read from indirectBuffer at indirectOffset bytes.

  2. Let workgroupCountY be an unsigned 32-bit integer read from indirectBuffer at (indirectOffset + 4) bytes.

  3. Let workgroupCountZ be an unsigned 32-bit integer read from indirectBuffer at (indirectOffset + 8) bytes.

  4. If workgroupCountX, workgroupCountY, or workgroupCountZ is greater than this.device.limits.maxComputeWorkgroupsPerDimension, return.

  5. Execute a grid of workgroups with dimensions [workgroupCountX, workgroupCountY, workgroupCountZ] with bindingState.[[pipeline]] using bindingState.[[bind_groups]].

16.1.3. Finalization

The compute pass encoder can be ended by calling end() once the user has finished recording commands for the pass. Once end() has been called the compute pass encoder can no longer be used.

end()

Completes recording of the compute pass commands sequence.

Called on: GPUComputePassEncoder this.

Returns: undefined

Content timeline steps:

  1. Issue the subsequent steps on the Device timeline of this.[[device]].

Device timeline steps:
  1. Let parentEncoder be this.[[command_encoder]].

  2. If any of the following requirements are unmet, generate a validation error and return.

  3. Set this.[[state]] to "ended".

  4. Set parentEncoder.[[state]] to "open".

  5. If any of the following requirements are unmet, invalidate parentEncoder and return.

  6. Extend parentEncoder.[[commands]] with this.[[commands]].

  7. If this.[[endTimestampWrite]] is not null:

    1. Extend parentEncoder.[[commands]] with this.[[endTimestampWrite]].

17. Render Passes

17.1. GPURenderPassEncoder

[Exposed=(Window, Worker), SecureContext]
interface GPURenderPassEncoder {
    undefined setViewport(float x, float y,
        float width, float height,
        float minDepth, float maxDepth);

    undefined setScissorRect(GPUIntegerCoordinate x, GPUIntegerCoordinate y,
                        GPUIntegerCoordinate width, GPUIntegerCoordinate height);

    undefined setBlendConstant(GPUColor color);
    undefined setStencilReference(GPUStencilValue reference);

    undefined beginOcclusionQuery(GPUSize32 queryIndex);
    undefined endOcclusionQuery();

    undefined executeBundles(sequence<GPURenderBundle> bundles);
    undefined end();
};
GPURenderPassEncoder includes GPUObjectBase;
GPURenderPassEncoder includes GPUCommandsMixin;
GPURenderPassEncoder includes GPUDebugCommandsMixin;
GPURenderPassEncoder includes GPUBindingCommandsMixin;
GPURenderPassEncoder includes GPURenderCommandsMixin;

GPURenderPassEncoder has the following device timeline properties:

[[command_encoder]], of type GPUCommandEncoder, readonly

The GPUCommandEncoder that created this render pass encoder.

[[attachment_size]], readonly

Set to the following extents:

  • width, height = the dimensions of the pass’s render attachments

[[occlusion_query_set]], of type GPUQuerySet, readonly

The GPUQuerySet to store occlusion query results for the pass, which is initialized with GPURenderPassDescriptor.occlusionQuerySet at pass creation time.

[[endTimestampWrite]], of type GPU command?, readonly, defaulting to null

GPU command, if any, writing a timestamp when the pass ends.

[[maxDrawCount]] of type GPUSize64, readonly

The maximum number of draws allowed in this pass.

[[occlusion_query_active]], of type boolean

Whether the pass’s [[occlusion_query_set]] is being written.

When executing encoded render pass commands as part of a GPUCommandBuffer, an internal RenderState object is used to track the current state required for rendering.

RenderState has the following queue timeline properties:

[[occlusionQueryIndex]], of type GPUSize32

The index into [[occlusion_query_set]] at which to store the occlusion query results.

[[viewport]]

Current viewport rectangle and depth range. Initially set to the following values:

  • x, y = 0.0, 0.0

  • width, height = the dimensions of the pass’s render targets

  • minDepth, maxDepth = 0.0, 1.0

[[scissorRect]]

Current scissor rectangle. Initially set to the following values:

  • x, y = 0, 0

  • width, height = the dimensions of the pass’s render targets

[[blendConstant]], of type GPUColor

Current blend constant value, initially [0, 0, 0, 0].

[[stencilReference]], of type GPUStencilValue

Current stencil reference value, initially 0.

[[colorAttachments]], of type sequence<GPURenderPassColorAttachment?>

The color attachments and state for this render pass.

[[depthStencilAttachment]], of type GPURenderPassDepthStencilAttachment?

The depth/stencil attachment and state for this render pass.

Render passes also have framebuffer memory, which contains the texel data associated with each attachment that is written into by draw commands and read from for blending and depth/stencil testing.

Note: Depending on the GPU hardware, framebuffer memory may be the memory allocated by the attachment textures or may be a separate area of memory that the texture data is copied to and from, such as with tile-based architectures.

17.1.1. Render Pass Encoder Creation

dictionary GPURenderPassTimestampWrites {
    required GPUQuerySet querySet;
    GPUSize32 beginningOfPassWriteIndex;
    GPUSize32 endOfPassWriteIndex;
};
querySet, of type GPUQuerySet

The GPUQuerySet, of type "timestamp", that the query results will be written to.

beginningOfPassWriteIndex, of type GPUSize32

If defined, indicates the query index in querySet into which the timestamp at the beginning of the render pass will be written.

endOfPassWriteIndex, of type GPUSize32

If defined, indicates the query index in querySet into which the timestamp at the end of the render pass will be written.

Note: Timestamp query values are written in nanoseconds, but how the value is determined is implementation-defined and may not increase monotonically. See § 20.4 Timestamp Query for details.

dictionary GPURenderPassDescriptor
         : GPUObjectDescriptorBase {
    required sequence<GPURenderPassColorAttachment?> colorAttachments;
    GPURenderPassDepthStencilAttachment depthStencilAttachment;
    GPUQuerySet occlusionQuerySet;
    GPURenderPassTimestampWrites timestampWrites;
    GPUSize64 maxDrawCount = 50000000;
};
colorAttachments, of type sequence<GPURenderPassColorAttachment?>

The set of GPURenderPassColorAttachment values in this sequence defines which color attachments will be output to when executing this render pass.

Due to usage compatibility, no color attachment may alias another attachment or any resource used inside the render pass.

depthStencilAttachment, of type GPURenderPassDepthStencilAttachment

The GPURenderPassDepthStencilAttachment value that defines the depth/stencil attachment that will be output to and tested against when executing this render pass.

Due to usage compatibility, no writable depth/stencil attachment may alias another attachment or any resource used inside the render pass.

occlusionQuerySet, of type GPUQuerySet

The GPUQuerySet value defines where the occlusion query results will be stored for this pass.

timestampWrites, of type GPURenderPassTimestampWrites

Defines which timestamp values will be written for this pass, and where to write them to.

maxDrawCount, of type GPUSize64, defaulting to 50000000

The maximum number of draw calls that will be done in the render pass. Used by some implementations to size work injected before the render pass. Keeping the default value is a good default, unless it is known that more draw calls will be done.

Valid Usage

Given a GPUDevice device and GPURenderPassDescriptor this, the following validation rules apply:

  1. this.colorAttachments.size must be ≤ device.[[limits]].maxColorAttachments.

  2. For each non-null colorAttachment in this.colorAttachments:

    1. colorAttachment.view must be valid to use with device.

    2. If colorAttachment.resolveTarget is provided:

      1. colorAttachment.resolveTarget must be valid to use with device.

    3. colorAttachment must meet the GPURenderPassColorAttachment Valid Usage rules.

  3. If this.depthStencilAttachment is provided:

    1. this.depthStencilAttachment.view must be valid to use with device.

    2. this.depthStencilAttachment must meet the GPURenderPassDepthStencilAttachment Valid Usage rules.

  4. There must exist at least one attachment, either:

  5. Validating GPURenderPassDescriptor’s color attachment bytes per sample(device, this.colorAttachments) succeeds.

  6. All views in non-null members of this.colorAttachments, and this.depthStencilAttachment.view if present, must have equal sampleCounts.

  7. For each view in non-null members of this.colorAttachments and this.depthStencilAttachment.view, if present, the [[renderExtent]] must match.

  8. If this.occlusionQuerySet is provided:

    1. this.occlusionQuerySet must be valid to use with device.

    2. this.occlusionQuerySet.type must be occlusion.

  9. If this.timestampWrites is provided:

Validating GPURenderPassDescriptor’s color attachment bytes per sample(device, colorAttachments)

Arguments:

Device timeline steps:

  1. Let formats be an empty list<GPUTextureFormat?>

  2. For each colorAttachment in colorAttachments:

    1. If colorAttachment is undefined, continue.

    2. Append colorAttachment.view.[[descriptor]].format to formats.

  3. Calculating color attachment bytes per sample(formats) must be ≤ device.[[limits]].maxColorAttachmentBytesPerSample.

17.1.1.1. Color Attachments
dictionary GPURenderPassColorAttachment {
    required (GPUTexture or GPUTextureView) view;
    GPUIntegerCoordinate depthSlice;
    (GPUTexture or GPUTextureView) resolveTarget;

    GPUColor clearValue;
    required GPULoadOp loadOp;
    required GPUStoreOp storeOp;
};
view, of type (GPUTexture or GPUTextureView)

Describes the texture subresource that will be output to for this color attachment. The subresource is determined by calling get as texture view(view).

depthSlice, of type GPUIntegerCoordinate

Indicates the depth slice index of "3d" view that will be output to for this color attachment.

resolveTarget, of type (GPUTexture or GPUTextureView)

Describes the texture subresource that will receive the resolved output for this color attachment if view is multisampled. The subresource is determined by calling get as texture view(resolveTarget).

clearValue, of type GPUColor

Indicates the value to clear view to prior to executing the render pass. If not provided, defaults to {r: 0, g: 0, b: 0, a: 0}. Ignored if loadOp is not "clear".

The components of clearValue are all double values. They are converted to a texel value of texture format matching the render attachment. If conversion fails, a validation error is generated.

loadOp, of type GPULoadOp

Indicates the load operation to perform on view prior to executing the render pass.

Note: It is recommended to prefer clearing; see "clear" for details.

storeOp, of type GPUStoreOp

The store operation to perform on view after executing the render pass.

GPURenderPassColorAttachment Valid Usage

Given a GPURenderPassColorAttachment this:

  1. Let renderViewDescriptor be this.view.[[descriptor]].

  2. Let renderTexture be this.view.[[texture]].

  3. All of the requirements in the following steps must be met.

    1. renderViewDescriptor.format must be a color renderable format.

    2. this.view must be a renderable texture view.

    3. If renderViewDescriptor.dimension is "3d":

      1. this.depthSlice must be provided and must be < the depthOrArrayLayers of the logical miplevel-specific texture extent of the renderTexture subresource at mipmap level renderViewDescriptor.baseMipLevel.

      Otherwise:

      1. this.depthSlice must not be provided.

    4. If this.loadOp is "clear":

      1. Converting the IDL value this.clearValue to a texel value of texture format renderViewDescriptor.format must not throw a TypeError.

        Note: An error is not thrown if the value is out-of-range for the format but in-range for the corresponding WGSL primitive type (f32, i32, or u32).

    5. If this.resolveTarget is provided:

      1. Let resolveViewDescriptor be this.resolveTarget.[[descriptor]].

      2. Let resolveTexture be this.resolveTarget.[[texture]].

      3. renderTexture.sampleCount must be > 1.

      4. resolveTexture.sampleCount must be 1.

      5. this.resolveTarget must be a non-3d renderable texture view.

      6. this.resolveTarget.[[renderExtent]] and this.view.[[renderExtent]] must match.

      7. resolveViewDescriptor.format must equal renderViewDescriptor.format.

      8. resolveTexture.format must equal renderTexture.format.

      9. resolveViewDescriptor.format must support resolve according to § 26.1.1 Plain color formats.

A GPUTextureView view is a renderable texture view if the all of the requirements in the following device timeline steps are met:
  1. Let descriptor be view.[[descriptor]].

  2. descriptor.usage must contain RENDER_ATTACHMENT.

  3. descriptor.dimension must be "2d" or "2d-array" or "3d".

  4. descriptor.mipLevelCount must be 1.

  5. descriptor.arrayLayerCount must be 1.

  6. descriptor.aspect must refer to all aspects of view.[[texture]].

Calculating color attachment bytes per sample(formats)

Arguments:

Returns: GPUSize32

  1. Let total be 0.

  2. For each non-null format in formats

    1. Assert: format is a color renderable format.

    2. Let renderTargetPixelByteCost be the render target pixel byte cost of format.

    3. Let renderTargetComponentAlignment be the render target component alignment of format.

    4. Round total up to the smallest multiple of renderTargetComponentAlignment greater than or equal to total.

    5. Add renderTargetPixelByteCost to total.

  3. Return total.

17.1.1.2. Depth/Stencil Attachments
dictionary GPURenderPassDepthStencilAttachment {
    required (GPUTexture or GPUTextureView) view;

    float depthClearValue;
    GPULoadOp depthLoadOp;
    GPUStoreOp depthStoreOp;
    boolean depthReadOnly = false;

    GPUStencilValue stencilClearValue = 0;
    GPULoadOp stencilLoadOp;
    GPUStoreOp stencilStoreOp;
    boolean stencilReadOnly = false;
};
view, of type (GPUTexture or GPUTextureView)

Describes the texture subresource that will be output to and read from for this depth/stencil attachment. The subresource is determined by calling get as texture view(view).

depthClearValue, of type float

Indicates the value to clear view’s depth component to prior to executing the render pass. Ignored if depthLoadOp is not "clear". Must be between 0.0 and 1.0, inclusive.

depthLoadOp, of type GPULoadOp

Indicates the load operation to perform on view’s depth component prior to executing the render pass.

Note: It is recommended to prefer clearing; see "clear" for details.

depthStoreOp, of type GPUStoreOp

The store operation to perform on view’s depth component after executing the render pass.

depthReadOnly, of type boolean, defaulting to false

Indicates that the depth component of view is read only.

stencilClearValue, of type GPUStencilValue, defaulting to 0

Indicates the value to clear view’s stencil component to prior to executing the render pass. Ignored if stencilLoadOp is not "clear".

The value will be converted to the type of the stencil aspect of view by taking the same number of LSBs as the number of bits in the stencil aspect of one texel of view.

stencilLoadOp, of type GPULoadOp

Indicates the load operation to perform on view’s stencil component prior to executing the render pass.

Note: It is recommended to prefer clearing; see "clear" for details.

stencilStoreOp, of type GPUStoreOp

The store operation to perform on view’s stencil component after executing the render pass.

stencilReadOnly, of type boolean, defaulting to false

Indicates that the stencil component of view is read only.

GPURenderPassDepthStencilAttachment Valid Usage

Given a GPURenderPassDepthStencilAttachment this, the following validation rules apply:

17.1.1.3. Load & Store Operations
enum GPULoadOp {
    "load",
    "clear",
};
"load"

Loads the existing value for this attachment into the render pass.

"clear"

Loads a clear value for this attachment into the render pass.

Note: On some GPU hardware (primarily mobile), "clear" is significantly cheaper because it avoids loading data from main memory into tile-local memory. On other GPU hardware, there isn’t a significant difference. As a result, it is recommended to use "clear" rather than "load" in cases where the initial value doesn’t matter (e.g. the render target will be cleared using a skybox).

enum GPUStoreOp {
    "store",
    "discard",
};
"store"

Stores the resulting value of the render pass for this attachment.

"discard"

Discards the resulting value of the render pass for this attachment.

Note: Discarded attachments behave as if they are cleared to zero, but implementations are not required to perform a clear at the end of the render pass. Implementations which do not explicitly clear discarded attachments at the end of a pass must lazily clear them prior to the reading the attachment contents, which occurs via sampling, copies, attaching to a later render pass with "load", displaying or reading back the canvas (get a copy of the image contents of a context), etc.

17.1.1.4. Render Pass Layout

GPURenderPassLayout declares the layout of the render targets of a GPURenderBundle. It is also used internally to describe GPURenderPassEncoder layouts and GPURenderPipeline layouts. It determines compatibility between render passes, render bundles, and render pipelines.

dictionary GPURenderPassLayout
         : GPUObjectDescriptorBase {
    required sequence<GPUTextureFormat?> colorFormats;
    GPUTextureFormat depthStencilFormat;
    GPUSize32 sampleCount = 1;
};
colorFormats, of type sequence<GPUTextureFormat?>

A list of the GPUTextureFormats of the color attachments for this pass or bundle.

depthStencilFormat, of type GPUTextureFormat

The GPUTextureFormat of the depth/stencil attachment for this pass or bundle.

sampleCount, of type GPUSize32, defaulting to 1

Number of samples per pixel in the attachments for this pass or bundle.

Two GPURenderPassLayout values are equal if:
derive render targets layout from pass

Arguments:

Returns: GPURenderPassLayout

Device timeline steps:

  1. Let layout be a new GPURenderPassLayout object.

  2. For each colorAttachment in descriptor.colorAttachments:

    1. If colorAttachment is not null:

      1. Set layout.sampleCount to colorAttachment.view.[[texture]].sampleCount.

      2. Append colorAttachment.view.[[descriptor]].format to layout.colorFormats.

    2. Otherwise:

      1. Append null to layout.colorFormats.

  3. Let depthStencilAttachment be descriptor.depthStencilAttachment.

  4. If depthStencilAttachment is not null:

    1. Let view be depthStencilAttachment.view.

    2. Set layout.sampleCount to view.[[texture]].sampleCount.

    3. Set layout.depthStencilFormat to view.[[descriptor]].format.

  5. Return layout.

derive render targets layout from pipeline

Arguments:

Returns: GPURenderPassLayout

Device timeline steps:

  1. Let layout be a new GPURenderPassLayout object.

  2. Set layout.sampleCount to descriptor.multisample.count.

  3. If descriptor.depthStencil is provided:

    1. Set layout.depthStencilFormat to descriptor.depthStencil.format.

  4. If descriptor.fragment is provided:

    1. For each colorTarget in descriptor.fragment.targets:

      1. Append colorTarget.format to layout.colorFormats if colorTarget is not null, or append null otherwise.

  5. Return layout.

17.1.2. Finalization

The render pass encoder can be ended by calling end() once the user has finished recording commands for the pass. Once end() has been called the render pass encoder can no longer be used.

end()

Completes recording of the render pass commands sequence.

Called on: GPURenderPassEncoder this.

Returns: undefined

Content timeline steps:

  1. Issue the subsequent steps on the Device timeline of this.[[device]].

Device timeline steps:
  1. Let parentEncoder be this.[[command_encoder]].

  2. If any of the following requirements are unmet, generate a validation error and return.

  3. Set this.[[state]] to "ended".

  4. Set parentEncoder.[[state]] to "open".

  5. If any of the following requirements are unmet, invalidate parentEncoder and return.

  6. Extend parentEncoder.[[commands]] with this.[[commands]].

  7. If this.[[endTimestampWrite]] is not null:

    1. Extend parentEncoder.[[commands]] with this.[[endTimestampWrite]].

  8. Enqueue a render command on this which issues the subsequent steps on the Queue timeline with renderState when executed.

Queue timeline steps:
  1. For each non-null colorAttachment in renderState.[[colorAttachments]]:

    1. Let colorView be colorAttachment.view.

    2. If colorView.[[descriptor]].dimension is:

      "3d"

      Let colorSubregion be colorAttachment.depthSlice of colorView.

      Otherwise

      Let colorSubregion be colorView.

    3. If colorAttachment.resolveTarget is not null:

      1. Resolve the multiple samples of every texel of colorSubregion to a single sample and copy to colorAttachment.resolveTarget.

    4. If colorAttachment.loadOp is:

      "store"

      Ensure the contents of the framebuffer memory associated with colorSubregion are stored in colorSubregion.

      "discard"

      Set every texel of colorSubregion to zero.

  2. Let depthStencilAttachment be renderState.[[depthStencilAttachment]].

  3. If depthStencilAttachment is not null:

    1. If depthStencilAttachment.depthLoadOp is:

      Not provided

      Assert that depthStencilAttachment.depthReadOnly is true and leave the depth subresource of depthStencilView unchanged.

      "store"

      Ensure the contents of the framebuffer memory associated with the depth subresource of depthStencilView are stored in depthStencilView.

      "discard"

      Set every texel in the depth subresource of depthStencilView to zero.

    2. If depthStencilAttachment.stencilLoadOp is:

      Not provided

      Assert that depthStencilAttachment.stencilReadOnly is true and leave the stencil subresource of depthStencilView unchanged.

      "store"

      Ensure the contents of the framebuffer memory associated with the stencil subresource of depthStencilView are stored in depthStencilView.

      "discard"

      Set every texel in the stencil subresource depthStencilView to zero.

  4. Let renderState be null.

Note: Discarded attachments behave as if they are cleared to zero, but implementations are not required to perform a clear at the end of the render pass. See the note on "discard" for additional details.

Note: Read-only depth-stencil attachments can be thought of as implicitly using the "store" operation, but since their content is unchanged during the render pass implementations don’t need to update the attachment. Validation that requires the store op to not be provided for read-only attachments is done in GPURenderPassDepthStencilAttachment Valid Usage.

17.2. GPURenderCommandsMixin

GPURenderCommandsMixin defines rendering commands common to GPURenderPassEncoder and GPURenderBundleEncoder.

interface mixin GPURenderCommandsMixin {
    undefined setPipeline(GPURenderPipeline pipeline);

    undefined setIndexBuffer(GPUBuffer buffer, GPUIndexFormat indexFormat, optional GPUSize64 offset = 0, optional GPUSize64 size);
    undefined setVertexBuffer(GPUIndex32 slot, GPUBuffer? buffer, optional GPUSize64 offset = 0, optional GPUSize64 size);

    undefined draw(GPUSize32 vertexCount, optional GPUSize32 instanceCount = 1,
        optional GPUSize32 firstVertex = 0, optional GPUSize32 firstInstance = 0);
    undefined drawIndexed(GPUSize32 indexCount, optional GPUSize32 instanceCount = 1,
        optional GPUSize32 firstIndex = 0,
        optional GPUSignedOffset32 baseVertex = 0,
        optional GPUSize32 firstInstance = 0);

    undefined drawIndirect(GPUBuffer indirectBuffer, GPUSize64 indirectOffset);
    undefined drawIndexedIndirect(GPUBuffer indirectBuffer, GPUSize64 indirectOffset);
};

GPURenderCommandsMixin assumes the presence of GPUObjectBase, GPUCommandsMixin, and GPUBindingCommandsMixin members on the same object. It must only be included by interfaces which also include those mixins.

GPURenderCommandsMixin has the following device timeline properties:

[[layout]], of type GPURenderPassLayout, readonly

The layout of the render pass.

[[depthReadOnly]], of type boolean, readonly

If true, indicates that the depth component is not modified.

[[stencilReadOnly]], of type boolean, readonly

If true, indicates that the stencil component is not modified.

[[usage scope]], of type usage scope, initially empty

The usage scope for this render pass or bundle.

[[pipeline]], of type GPURenderPipeline, initially null

The current GPURenderPipeline.

[[index_buffer]], of type GPUBuffer, initially null

The current buffer to read index data from.

[[index_format]], of type GPUIndexFormat

The format of the index data in [[index_buffer]].

[[index_buffer_offset]], of type GPUSize64

The offset in bytes of the section of [[index_buffer]] currently set.

[[index_buffer_size]], of type GPUSize64

The size in bytes of the section of [[index_buffer]] currently set, initially 0.

[[vertex_buffers]], of type ordered map<slot, GPUBuffer>, initially empty

The current GPUBuffers to read vertex data from for each slot.

[[vertex_buffer_sizes]], of type ordered map<slot, GPUSize64>, initially empty

The size in bytes of the section of GPUBuffer currently set for each slot.

[[drawCount]], of type GPUSize64

The number of draw commands recorded in this encoder.

To Enqueue a render command on GPURenderCommandsMixin encoder which issues the steps of a GPU Command command with RenderState renderState, run the following device timeline steps:
  1. Append command to encoder.[[commands]].

  2. When command is executed as part of a GPUCommandBuffer commandBuffer:

    1. Issue the steps of command with commandBuffer.[[renderState]] as renderState.

17.2.1. Drawing

setPipeline(pipeline)

Sets the current GPURenderPipeline.

Called on: GPURenderCommandsMixin this.

Arguments:

Arguments for the GPURenderCommandsMixin.setPipeline(pipeline) method.
Parameter Type Nullable Optional Description
pipeline GPURenderPipeline The render pipeline to use for subsequent drawing commands.

Returns: undefined

Content timeline steps:

  1. Issue the subsequent steps on the Device timeline of this.[[device]].

Device timeline steps:
  1. Validate the encoder state of this. If it returns false, return.

  2. Let pipelineTargetsLayout be derive render targets layout from pipeline(pipeline.[[descriptor]]).

  3. If any of the following conditions are unsatisfied, invalidate this and return.

  4. Set this.[[pipeline]] to be pipeline.

setIndexBuffer(buffer, indexFormat, offset, size)

Sets the current index buffer.

Called on: GPURenderCommandsMixin this.

Arguments:

Arguments for the GPURenderCommandsMixin.setIndexBuffer(buffer, indexFormat, offset, size) method.
Parameter Type Nullable Optional Description
buffer GPUBuffer Buffer containing index data to use for subsequent drawing commands.
indexFormat GPUIndexFormat Format of the index data contained in buffer.
offset GPUSize64 Offset in bytes into buffer where the index data begins. Defaults to 0.
size GPUSize64 Size in bytes of the index data in buffer. Defaults to the size of the buffer minus the offset.

Returns: undefined

Content timeline steps:

  1. Issue the subsequent steps on the Device timeline of this.[[device]].

Device timeline steps:
  1. Validate the encoder state of this. If it returns false, return.

  2. If size is missing, set size to max(0, buffer.size - offset).

  3. If any of the following conditions are unsatisfied, invalidate this and return.

  4. Add buffer to [[usage scope]] with usage input.

  5. Set this.[[index_buffer]] to be buffer.

  6. Set this.[[index_format]] to be indexFormat.

  7. Set this.[[index_buffer_offset]] to be offset.

  8. Set this.[[index_buffer_size]] to be size.

setVertexBuffer(slot, buffer, offset, size)

Sets the current vertex buffer for the given slot.

Called on: GPURenderCommandsMixin this.

Arguments:

Arguments for the GPURenderCommandsMixin.setVertexBuffer(slot, buffer, offset, size) method.
Parameter Type Nullable Optional Description
slot GPUIndex32 The vertex buffer slot to set the vertex buffer for.
buffer GPUBuffer? Buffer containing vertex data to use for subsequent drawing commands.
offset GPUSize64 Offset in bytes into buffer where the vertex data begins. Defaults to 0.
size GPUSize64 Size in bytes of the vertex data in buffer. Defaults to the size of the buffer minus the offset.

Returns: undefined

Content timeline steps:

  1. Issue the subsequent steps on the Device timeline of this.[[device]].

Device timeline steps:
  1. Validate the encoder state of this. If it returns false, return.

  2. Let bufferSize be 0 if buffer is null, or buffer.size if not.

  3. If size is missing, set size to max(0, bufferSize - offset).

  4. If any of the following requirements are unmet, invalidate this and return.

  5. If buffer is null:

    1. Remove this.[[vertex_buffers]][slot].

    2. Remove this.[[vertex_buffer_sizes]][slot].

    Otherwise:

    1. If any of the following requirements are unmet, invalidate this and return.

    2. Add buffer to [[usage scope]] with usage input.

    3. Set this.[[vertex_buffers]][slot] to be buffer.

    4. Set this.[[vertex_buffer_sizes]][slot] to be size.

draw(vertexCount, instanceCount, firstVertex, firstInstance)

Draws primitives. See § 23.2 Rendering for the detailed specification.

Called on: GPURenderCommandsMixin this.

Arguments:

Arguments for the GPURenderCommandsMixin.draw(vertexCount, instanceCount, firstVertex, firstInstance) method.
Parameter Type Nullable Optional Description
vertexCount GPUSize32 The number of vertices to draw.
instanceCount GPUSize32 The number of instances to draw.
firstVertex GPUSize32 Offset into the vertex buffers, in vertices, to begin drawing from.
firstInstance GPUSize32 First instance to draw.

Returns: undefined

Content timeline steps:

  1. Issue the subsequent steps on the Device timeline of this.[[device]].

Device timeline steps:
  1. Validate the encoder state of this. If it returns false, return.

  2. All of the requirements in the following steps must be met. If any are unmet, invalidate this and return.

    1. It must be valid to draw with this.

    2. Let buffers be this.[[pipeline]].[[descriptor]].vertex.buffers.

    3. For each GPUIndex32 slot from 0 to buffers.size (non-inclusive):

      1. If buffers[slot] is null, continue.

      2. Let bufferSize be this.[[vertex_buffer_sizes]][slot].

      3. Let stride be buffers[slot].arrayStride.

      4. Let attributes be buffers[slot].attributes

      5. Let lastStride be the maximum value of (attribute.offset + byteSize(attribute.format)) over each attribute in attributes, or 0 if attributes is empty.

      6. Let strideCount be computed based on buffers[slot].stepMode:

        "vertex"

        firstVertex + vertexCount

        "instance"

        firstInstance + instanceCount

      7. If strideCount0:

        1. (strideCount1) × stride + lastStride must be ≤ bufferSize.

  3. Increment this.[[drawCount]] by 1.

  4. Let bindingState be a snapshot of this’s current state.

  5. Enqueue a render command on this which issues the subsequent steps on the Queue timeline with renderState when executed.

Queue timeline steps:
  1. Draw instanceCount instances, starting with instance firstInstance, of primitives consisting of vertexCount vertices, starting with vertex firstVertex, with the states from bindingState and renderState.

drawIndexed(indexCount, instanceCount, firstIndex, baseVertex, firstInstance)

Draws indexed primitives. See § 23.2 Rendering for the detailed specification.

Called on: GPURenderCommandsMixin this.

Arguments:

Arguments for the GPURenderCommandsMixin.drawIndexed(indexCount, instanceCount, firstIndex, baseVertex, firstInstance) method.
Parameter Type Nullable Optional Description
indexCount GPUSize32 The number of indices to draw.
instanceCount GPUSize32 The number of instances to draw.
firstIndex GPUSize32 Offset into the index buffer, in indices, begin drawing from.
baseVertex GPUSignedOffset32 Added to each index value before indexing into the vertex buffers.
firstInstance GPUSize32 First instance to draw.

Returns: undefined

Content timeline steps:

  1. Issue the subsequent steps on the Device timeline of this.[[device]].

Device timeline steps:
  1. Validate the encoder state of this. If it returns false, return.

  2. If any of the following conditions are unsatisfied, invalidate this and return.

  3. Increment this.[[drawCount]] by 1.

  4. Let bindingState be a snapshot of this’s current state.

  5. Enqueue a render command on this which issues the subsequent steps on the Queue timeline with renderState when executed.

Queue timeline steps:
  1. Draw instanceCount instances, starting with instance firstInstance, of primitives consisting of indexCount indexed vertices, starting with index firstIndex from vertex baseVertex, with the states from bindingState and renderState.

Note: WebGPU applications should never use index data with indices out of bounds of any bound vertex buffer that has GPUVertexStepMode "vertex". WebGPU implementations have different ways of handling this, and therefore a range of behaviors is allowed. Either the whole draw call is discarded, or the access to those attributes out of bounds is described by WGSL’s invalid memory reference.

drawIndirect(indirectBuffer, indirectOffset)

Draws primitives using parameters read from a GPUBuffer. See § 23.2 Rendering for the detailed specification.

The indirect draw parameters encoded in the buffer must be a tightly packed block of four 32-bit unsigned integer values (16 bytes total), given in the same order as the arguments for draw(). For example:

let drawIndirectParameters = new Uint32Array(4);
drawIndirectParameters[0] = vertexCount;
drawIndirectParameters[1] = instanceCount;
drawIndirectParameters[2] = firstVertex;
drawIndirectParameters[3] = firstInstance;

The value corresponding to firstInstance must be 0, unless the "indirect-first-instance" feature is enabled. If the "indirect-first-instance" feature is not enabled and firstInstance is not zero the drawIndirect() call will be treated as a no-op.

Called on: GPURenderCommandsMixin this.

Arguments:

Arguments for the GPURenderCommandsMixin.drawIndirect(indirectBuffer, indirectOffset) method.
Parameter Type Nullable Optional Description
indirectBuffer GPUBuffer Buffer containing the indirect draw parameters.
indirectOffset GPUSize64 Offset in bytes into indirectBuffer where the drawing data begins.

Returns: undefined

Content timeline steps:

  1. Issue the subsequent steps on the Device timeline of this.[[device]].

Device timeline steps:
  1. Validate the encoder state of this. If it returns false, return.

  2. If any of the following conditions are unsatisfied, invalidate this and return.

  3. Add indirectBuffer to [[usage scope]] with usage input.

  4. Increment this.[[drawCount]] by 1.

  5. Let bindingState be a snapshot of this’s current state.

  6. Enqueue a render command on this which issues the subsequent steps on the Queue timeline with renderState when executed.

Queue timeline steps:
  1. Let vertexCount be an unsigned 32-bit integer read from indirectBuffer at indirectOffset bytes.

  2. Let instanceCount be an unsigned 32-bit integer read from indirectBuffer at (indirectOffset + 4) bytes.

  3. Let firstVertex be an unsigned 32-bit integer read from indirectBuffer at (indirectOffset + 8) bytes.

  4. Let firstInstance be an unsigned 32-bit integer read from indirectBuffer at (indirectOffset + 12) bytes.

  5. Draw instanceCount instances, starting with instance firstInstance, of primitives consisting of vertexCount vertices, starting with vertex firstVertex, with the states from bindingState and renderState.

drawIndexedIndirect(indirectBuffer, indirectOffset)

Draws indexed primitives using parameters read from a GPUBuffer. See § 23.2 Rendering for the detailed specification.

The indirect drawIndexed parameters encoded in the buffer must be a tightly packed block of five 32-bit values (20 bytes total), given in the same order as the arguments for drawIndexed(). The value corresponding to baseVertex is a signed 32-bit integer, and all others are unsigned 32-bit integers. For example:

let drawIndexedIndirectParameters = new Uint32Array(5);
let drawIndexedIndirectParametersSigned = new Int32Array(drawIndexedIndirectParameters.buffer);
drawIndexedIndirectParameters[0] = indexCount;
drawIndexedIndirectParameters[1] = instanceCount;
drawIndexedIndirectParameters[2] = firstIndex;
// baseVertex is a signed value.
drawIndexedIndirectParametersSigned[3] = baseVertex;
drawIndexedIndirectParameters[4] = firstInstance;

The value corresponding to firstInstance must be 0, unless the "indirect-first-instance" feature is enabled. If the "indirect-first-instance" feature is not enabled and firstInstance is not zero the drawIndexedIndirect() call will be treated as a no-op.

Called on: GPURenderCommandsMixin this.

Arguments:

Arguments for the GPURenderCommandsMixin.drawIndexedIndirect(indirectBuffer, indirectOffset) method.
Parameter Type Nullable Optional Description
indirectBuffer GPUBuffer Buffer containing the indirect drawIndexed parameters.
indirectOffset GPUSize64 Offset in bytes into indirectBuffer where the drawing data begins.

Returns: undefined

Content timeline steps:

  1. Issue the subsequent steps on the Device timeline of this.[[device]].

Device timeline steps:
  1. Validate the encoder state of this. If it returns false, return.

  2. If any of the following conditions are unsatisfied, invalidate this and return.

  3. Add indirectBuffer to [[usage scope]] with usage input.

  4. Increment this.[[drawCount]] by 1.

  5. Let bindingState be a snapshot of this’s current state.

  6. Enqueue a render command on this which issues the subsequent steps on the Queue timeline with renderState when executed.

Queue timeline steps:
  1. Let indexCount be an unsigned 32-bit integer read from indirectBuffer at indirectOffset bytes.

  2. Let instanceCount be an unsigned 32-bit integer read from indirectBuffer at (indirectOffset + 4) bytes.

  3. Let firstIndex be an unsigned 32-bit integer read from indirectBuffer at (indirectOffset + 8) bytes.

  4. Let baseVertex be a signed 32-bit integer read from indirectBuffer at (indirectOffset + 12) bytes.

  5. Let firstInstance be an unsigned 32-bit integer read from indirectBuffer at (indirectOffset + 16) bytes.

  6. Draw instanceCount instances, starting with instance firstInstance, of primitives consisting of indexCount indexed vertices, starting with index firstIndex from vertex baseVertex, with the states from bindingState and renderState.

To determine if it’s valid to draw with GPURenderCommandsMixin encoder, run the following device timeline steps:
  1. If any of the following conditions are unsatisfied, return false:

  2. Otherwise return true.

To determine if it’s valid to draw indexed with GPURenderCommandsMixin encoder, run the following device timeline steps:
  1. If any of the following conditions are unsatisfied, return false:

  2. Otherwise return true.

17.2.2. Rasterization state

The GPURenderPassEncoder has several methods which affect how draw commands are rasterized to attachments used by this encoder.

setViewport(x, y, width, height, minDepth, maxDepth)

Sets the viewport used during the rasterization stage to linearly map from normalized device coordinates to viewport coordinates.

Called on: GPURenderPassEncoder this.

Arguments:

Arguments for the GPURenderPassEncoder.setViewport(x, y, width, height, minDepth, maxDepth) method.
Parameter Type Nullable Optional Description
x float Minimum X value of the viewport in pixels.
y float Minimum Y value of the viewport in pixels.
width float Width of the viewport in pixels.
height float Height of the viewport in pixels.
minDepth float Minimum depth value of the viewport.
maxDepth float Maximum depth value of the viewport.

Returns: undefined

Content timeline steps:

  1. Issue the subsequent steps on the Device timeline of this.[[device]].

Device timeline steps:
  1. Validate the encoder state of this. If it returns false, return.

  2. Let maxViewportRange be this.limits.maxTextureDimension2D × 2.

  3. If any of the following conditions are unsatisfied, invalidate this and return.

    • x ≥ -maxViewportRange

    • y ≥ -maxViewportRange

    • 0widththis.limits.maxTextureDimension2D

    • 0heightthis.limits.maxTextureDimension2D

    • x + widthmaxViewportRange1

    • y + heightmaxViewportRange1

    • 0.0minDepth1.0

    • 0.0maxDepth1.0

    • minDepthmaxDepth

  4. Enqueue a render command on this which issues the subsequent steps on the Queue timeline with renderState when executed.

Queue timeline steps:
  1. Round x, y, width, and height to some uniform precision, no less precise than integer rounding.

  2. Set renderState.[[viewport]] to the extents x, y, width, height, minDepth, and maxDepth.

setScissorRect(x, y, width, height)

Sets the scissor rectangle used during the rasterization stage. After transformation into viewport coordinates any fragments which fall outside the scissor rectangle will be discarded.

Called on: GPURenderPassEncoder this.

Arguments:

Arguments for the GPURenderPassEncoder.setScissorRect(x, y, width, height) method.
Parameter Type Nullable Optional Description
x GPUIntegerCoordinate Minimum X value of the scissor rectangle in pixels.
y GPUIntegerCoordinate Minimum Y value of the scissor rectangle in pixels.
width GPUIntegerCoordinate Width of the scissor rectangle in pixels.
height GPUIntegerCoordinate Height of the scissor rectangle in pixels.

Returns: undefined

Content timeline steps:

  1. Issue the subsequent steps on the Device timeline of this.[[device]].

Device timeline steps:
  1. Validate the encoder state of this. If it returns false, return.

  2. If any of the following conditions are unsatisfied, invalidate this and return.

  3. Enqueue a render command on this which issues the subsequent steps on the Queue timeline with renderState when executed.

Queue timeline steps:
  1. Set renderState.[[scissorRect]] to the extents x, y, width, and height.

setBlendConstant(color)

Sets the constant blend color and alpha values used with "constant" and "one-minus-constant" GPUBlendFactors.

Called on: GPURenderPassEncoder this.

Arguments:

Arguments for the GPURenderPassEncoder.setBlendConstant(color) method.
Parameter Type Nullable Optional Description
color GPUColor The color to use when blending.

Returns: undefined

Content timeline steps:

  1. ? validate GPUColor shape(color).

  2. Issue the subsequent steps on the Device timeline of this.[[device]].

Device timeline steps:
  1. Validate the encoder state of this. If it returns false, return.

  2. Enqueue a render command on this which issues the subsequent steps on the Queue timeline with renderState when executed.

Queue timeline steps:
  1. Set renderState.[[blendConstant]] to color.

setStencilReference(reference)

Sets the [[stencilReference]] value used during stencil tests with the "replace" GPUStencilOperation.

Called on: GPURenderPassEncoder this.

Arguments:

Arguments for the GPURenderPassEncoder.setStencilReference(reference) method.
Parameter Type Nullable Optional Description
reference GPUStencilValue The new stencil reference value.

Returns: undefined

Content timeline steps:

  1. Issue the subsequent steps on the Device timeline of this.[[device]].

Device timeline steps:
  1. Validate the encoder state of this. If it returns false, return.

  2. Enqueue a render command on this which issues the subsequent steps on the Queue timeline with renderState when executed.

Queue timeline steps:
  1. Set renderState.[[stencilReference]] to reference.

17.2.3. Queries

beginOcclusionQuery(queryIndex)
Called on: GPURenderPassEncoder this.

Arguments:

Arguments for the GPURenderPassEncoder.beginOcclusionQuery(queryIndex) method.
Parameter Type Nullable Optional Description
queryIndex GPUSize32 The index of the query in the query set.

Returns: undefined

Content timeline steps:

  1. Issue the subsequent steps on the Device timeline of this.[[device]].

Device timeline steps:
  1. Validate the encoder state of this. If it returns false, return.

  2. If any of the following conditions are unsatisfied, invalidate this and return.

  3. Set this.[[occlusion_query_active]] to true.

  4. Enqueue a render command on this which issues the subsequent steps on the Queue timeline with renderState when executed.

Queue timeline steps:
  1. Set renderState.[[occlusionQueryIndex]] to queryIndex.

endOcclusionQuery()
Called on: GPURenderPassEncoder this.

Returns: undefined

Content timeline steps:

  1. Issue the subsequent steps on the Device timeline of this.[[device]].

Device timeline steps:
  1. Validate the encoder state of this. If it returns false, return.

  2. If any of the following conditions are unsatisfied, invalidate this and return.

  3. Set this.[[occlusion_query_active]] to false.

  4. Enqueue a render command on this which issues the subsequent steps on the Queue timeline with renderState when executed.

Queue timeline steps:
  1. Let passingFragments be non-zero if any fragment samples passed all per-fragment tests since the corresponding beginOcclusionQuery() command was executed, and zero otherwise.

    Note: If no draw calls occurred, passingFragments is zero.

  2. Write passingFragments into this.[[occlusion_query_set]] at index renderState.[[occlusionQueryIndex]].

17.2.4. Bundles

executeBundles(bundles)

Executes the commands previously recorded into the given GPURenderBundles as part of this render pass.

When a GPURenderBundle is executed, it does not inherit the render pass’s pipeline, bind groups, or vertex and index buffers. After a GPURenderBundle has executed, the render pass’s pipeline, bind group, and vertex/index buffer state is cleared (to the initial, empty values).

Note: The state is cleared, not restored to the previous state. This occurs even if zero GPURenderBundles are executed.

Called on: GPURenderPassEncoder this.

Arguments:

Arguments for the GPURenderPassEncoder.executeBundles(bundles) method.
Parameter Type Nullable Optional Description
bundles sequence<GPURenderBundle> List of render bundles to execute.

Returns: undefined

Content timeline steps:

  1. Issue the subsequent steps on the Device timeline of this.[[device]].

Device timeline steps:
  1. Validate the encoder state of this. If it returns false, return.

  2. If any of the following conditions are unsatisfied, invalidate this and return.

  3. For each bundle in bundles:

    1. Increment this.[[drawCount]] by bundle.[[drawCount]].

    2. Merge bundle.[[usage scope]] into this.[[usage scope]].

    3. Enqueue a render command on this which issues the following steps on the Queue timeline with renderState when executed:

      Queue timeline steps:
      1. Execute each command in bundle.[[command_list]] with renderState.

        Note: renderState cannot be changed by executing render bundles. Binding state was already captured at bundle encoding time, and so isn’t used when executing bundles.

  4. Reset the render pass binding state of this.

To Reset the render pass binding state of GPURenderPassEncoder encoder run the following device timeline steps:
  1. Clear encoder.[[bind_groups]].

  2. Set encoder.[[pipeline]] to null.

  3. Set encoder.[[index_buffer]] to null.

  4. Clear encoder.[[vertex_buffers]].

18. Bundles

A bundle is a partial, limited pass that is encoded once and can then be executed multiple times as part of future pass encoders without expiring after use like typical command buffers. This can reduce the overhead of encoding and submission of commands which are issued repeatedly without changing.

18.1. GPURenderBundle

[Exposed=(Window, Worker), SecureContext]
interface GPURenderBundle {
};
GPURenderBundle includes GPUObjectBase;
[[command_list]], of type list<GPU command>

A list of GPU commands to be submitted to the GPURenderPassEncoder when the GPURenderBundle is executed.

[[usage scope]], of type usage scope, initially empty

The usage scope for this render bundle, stored for later merging into the GPURenderPassEncoder’s [[usage scope]] in executeBundles().

[[layout]], of type GPURenderPassLayout

The layout of the render bundle.

[[depthReadOnly]], of type boolean

If true, indicates that the depth component is not modified by executing this render bundle.

[[stencilReadOnly]], of type boolean

If true, indicates that the stencil component is not modified by executing this render bundle.

[[drawCount]], of type GPUSize64

The number of draw commands in this GPURenderBundle.

18.1.1. Render Bundle Creation

dictionary GPURenderBundleDescriptor
         : GPUObjectDescriptorBase {
};
[Exposed=(Window, Worker), SecureContext]
interface GPURenderBundleEncoder {
    GPURenderBundle finish(optional GPURenderBundleDescriptor descriptor = {});
};
GPURenderBundleEncoder includes GPUObjectBase;
GPURenderBundleEncoder includes GPUCommandsMixin;
GPURenderBundleEncoder includes GPUDebugCommandsMixin;
GPURenderBundleEncoder includes GPUBindingCommandsMixin;
GPURenderBundleEncoder includes GPURenderCommandsMixin;
createRenderBundleEncoder(descriptor)

Creates a GPURenderBundleEncoder.

Called on: GPUDevice this.

Arguments:

Arguments for the GPUDevice.createRenderBundleEncoder(descriptor) method.
Parameter Type Nullable Optional Description
descriptor GPURenderBundleEncoderDescriptor Description of the GPURenderBundleEncoder to create.

Returns: GPURenderBundleEncoder

Content timeline steps:

  1. ? Validate texture format required features of each non-null element of descriptor.colorFormats with this.[[device]].

  2. If descriptor.depthStencilFormat is provided:

    1. ? Validate texture format required features of descriptor.depthStencilFormat with this.[[device]].

  3. Let e be ! create a new WebGPU object(this, GPURenderBundleEncoder, descriptor).

  4. Issue the initialization steps on the Device timeline of this.

  5. Return e.

Device timeline initialization steps:
  1. If any of the following conditions are unsatisfied generate a validation error, invalidate e and return.

  2. Set e.[[layout]] to a copy of descriptor’s included GPURenderPassLayout interface.

  3. Set e.[[depthReadOnly]] to descriptor.depthReadOnly.

  4. Set e.[[stencilReadOnly]] to descriptor.stencilReadOnly.

  5. Set e.[[state]] to "open".

  6. Set e.[[drawCount]] to 0.

18.1.2. Encoding

dictionary GPURenderBundleEncoderDescriptor
         : GPURenderPassLayout {
    boolean depthReadOnly = false;
    boolean stencilReadOnly = false;
};
depthReadOnly, of type boolean, defaulting to false

If true, indicates that the render bundle does not modify the depth component of the GPURenderPassDepthStencilAttachment of any render pass the render bundle is executed in.

See read-only depth-stencil.

stencilReadOnly, of type boolean, defaulting to false

If true, indicates that the render bundle does not modify the stencil component of the GPURenderPassDepthStencilAttachment of any render pass the render bundle is executed in.

See read-only depth-stencil.

18.1.3. Finalization

finish(descriptor)

Completes recording of the render bundle commands sequence.

Called on: GPURenderBundleEncoder this.

Arguments:

Arguments for the GPURenderBundleEncoder.finish(descriptor) method.
Parameter Type Nullable Optional Description
descriptor GPURenderBundleDescriptor

Returns: GPURenderBundle

Content timeline steps:

  1. Let renderBundle be a new GPURenderBundle.

  2. Issue the finish steps on the Device timeline of this.[[device]].

  3. Return renderBundle.

Device timeline finish steps:
  1. Let validationSucceeded be true if all of the following requirements are met, and false otherwise.

  2. Set this.[[state]] to "ended".

  3. If validationSucceeded is false, then:

    1. Generate a validation error.

    2. Return an invalidated GPURenderBundle.

  4. Set renderBundle.[[command_list]] to this.[[commands]].

  5. Set renderBundle.[[usage scope]] to this.[[usage scope]].

  6. Set renderBundle.[[drawCount]] to this.[[drawCount]].

19. Queues

19.1. GPUQueueDescriptor

GPUQueueDescriptor describes a queue request.

dictionary GPUQueueDescriptor
         : GPUObjectDescriptorBase {
};

19.2. GPUQueue

[Exposed=(Window, Worker), SecureContext]
interface GPUQueue {
    undefined submit(sequence<GPUCommandBuffer> commandBuffers);

    Promise<undefined> onSubmittedWorkDone();

    undefined writeBuffer(
        GPUBuffer buffer,
        GPUSize64 bufferOffset,
        AllowSharedBufferSource data,
        optional GPUSize64 dataOffset = 0,
        optional GPUSize64 size);

    undefined writeTexture(
        GPUTexelCopyTextureInfo destination,
        AllowSharedBufferSource data,
        GPUTexelCopyBufferLayout dataLayout,
        GPUExtent3D size);

    undefined copyExternalImageToTexture(
        GPUCopyExternalImageSourceInfo source,
        GPUCopyExternalImageDestInfo destination,
        GPUExtent3D copySize);
};
GPUQueue includes GPUObjectBase;

GPUQueue has the following methods:

writeBuffer(buffer, bufferOffset, data, dataOffset, size)

Issues a write operation of the provided data into a GPUBuffer.

Called on: GPUQueue this.

Arguments:

Arguments for the GPUQueue.writeBuffer(buffer, bufferOffset, data, dataOffset, size) method.
Parameter Type Nullable Optional Description
buffer GPUBuffer The buffer to write to.
bufferOffset GPUSize64 Offset in bytes into buffer to begin writing at.
data AllowSharedBufferSource Data to write into buffer.
dataOffset GPUSize64 Offset in into data to begin writing from. Given in elements if data is a TypedArray and bytes otherwise.
size GPUSize64 Size of content to write from data to buffer. Given in elements if data is a TypedArray and bytes otherwise.

Returns: undefined

Content timeline steps:

  1. If data is an ArrayBuffer or DataView, let the element type be "byte". Otherwise, data is a TypedArray; let the element type be the type of the TypedArray.

  2. Let dataSize be the size of data, in elements.

  3. If size is missing, let contentsSize be dataSizedataOffset. Otherwise, let contentsSize be size.

  4. If any of the following conditions are unsatisfied, throw an OperationError and return.

    • contentsSize ≥ 0.

    • dataOffset + contentsSizedataSize.

    • contentsSize, converted to bytes, is a multiple of 4 bytes.

  5. Let dataContents be a copy of the bytes held by the buffer source data.

  6. Let contents be the contentsSize elements of dataContents starting at an offset of dataOffset elements.

  7. Issue the subsequent steps on the Device timeline of this.

Device timeline steps:
  1. If any of the following conditions are unsatisfied, generate a validation error and return.

  2. Issue the subsequent steps on the Queue timeline of this.

Queue timeline steps:
  1. Write contents into buffer starting at bufferOffset.

writeTexture(destination, data, dataLayout, size)

Issues a write operation of the provided data into a GPUTexture.

Called on: GPUQueue this.

Arguments:

Arguments for the GPUQueue.writeTexture(destination, data, dataLayout, size) method.
Parameter Type Nullable Optional Description
destination GPUTexelCopyTextureInfo The texture subresource and origin to write to.
data AllowSharedBufferSource Data to write into destination.
dataLayout GPUTexelCopyBufferLayout Layout of the content in data.
size GPUExtent3D Extents of the content to write from data to destination.

Returns: undefined

Content timeline steps:

  1. ? validate GPUOrigin3D shape(destination.origin).

  2. ? validate GPUExtent3D shape(size).

  3. Let dataBytes be a copy of the bytes held by the buffer source data.

    Note: This is described as copying all of data to the device timeline, but in practice data could be much larger than necessary. Implementations should optimize by copying only the necessary bytes.

  4. Issue the subsequent steps on the Device timeline of this.

Device timeline steps:
  1. Let aligned be false.

  2. Let dataLength be dataBytes.length.

  3. If any of the following conditions are unsatisfied, generate a validation error and return.

    Note: unlike GPUCommandEncoder.copyBufferToTexture(), there is no alignment requirement on either dataLayout.bytesPerRow or dataLayout.offset.

  4. Issue the subsequent steps on the Queue timeline of this.

Queue timeline steps:
  1. Let blockWidth be the texel block width of destination.texture.

  2. Let blockHeight be the texel block height of destination.texture.

  3. Let dstOrigin be destination.origin;

  4. Let dstBlockOriginX be (dstOrigin.x ÷ blockWidth).

  5. Let dstBlockOriginY be (dstOrigin.y ÷ blockHeight).

  6. Let blockColumns be (copySize.width ÷ blockWidth).

  7. Let blockRows be (copySize.height ÷ blockHeight).

  8. Assert that dstBlockOriginX, dstBlockOriginY, blockColumns, and blockRows are integers.

  9. For each z in the range [0, copySize.depthOrArrayLayers − 1]:

    1. Let dstSubregion be texture copy sub-region (z + dstOrigin.z) of destination.

    2. For each y in the range [0, blockRows − 1]:

      1. For each x in the range [0, blockColumns − 1]:

        1. Let blockOffset be the texel block byte offset of dataLayout for (x, y, z) of destination.texture.

        2. Set texel block (dstBlockOriginX + x, dstBlockOriginY + y) of dstSubregion to be an equivalent texel representation to the texel block described by dataBytes at offset blockOffset.

copyExternalImageToTexture(source, destination, copySize)

Issues a copy operation of the contents of a platform image/canvas into the destination texture.

This operation performs color encoding into the destination encoding according to the parameters of GPUCopyExternalImageDestInfo.

Copying into a -srgb texture results in the same texture bytes, not the same decoded values, as copying into the corresponding non--srgb format. Thus, after a copy operation, sampling the destination texture has different results depending on whether its format is -srgb, all else unchanged.

NOTE:
When copying from a "webgl"/"webgl2" context canvas, the WebGL Drawing Buffer may be not exist during certain points in the frame presentation cycle (after the image has been moved to the compositor for display). To avoid this, either:
  • Issue copyExternalImageToTexture() in the same task with WebGL rendering operation, to ensure the copy occurs before the WebGL canvas is presented.

  • If not possible, set the preserveDrawingBuffer option in WebGLContextAttributes to true, so that the drawing buffer will still contain a copy of the frame contents after they’ve been presented. Note, this extra copy may have a performance cost.

Called on: GPUQueue this.

Arguments:

Arguments for the GPUQueue.copyExternalImageToTexture(source, destination, copySize) method.
Parameter Type Nullable Optional Description
source GPUCopyExternalImageSourceInfo source image and origin to copy to destination.
destination GPUCopyExternalImageDestInfo The texture subresource and origin to write to, and its encoding metadata.
copySize GPUExtent3D Extents of the content to write from source to destination.

Returns: undefined

Content timeline steps:

  1. ? validate GPUOrigin2D shape(source.origin).

  2. ? validate GPUOrigin3D shape(destination.origin).

  3. ? validate GPUExtent3D shape(copySize).

  4. Let sourceImage be source.source

  5. If sourceImage is not origin-clean, throw a SecurityError and return.

  6. If any of the following requirements are unmet, throw an OperationError and return.

    • source.origin.x + copySize.width must be ≤ the width of sourceImage.

    • source.origin.y + copySize.height must be ≤ the height of sourceImage.

    • copySize.depthOrArrayLayers must be ≤ 1.

  7. Let usability be ? check the usability of the image argument(source).

  8. Issue the subsequent steps on the Device timeline of this.

Device timeline steps:
  1. Let texture be destination.texture.

  2. If any of the following requirements are unmet, generate a validation error and return.

  3. If copySize.depthOrArrayLayers is > 0, issue the subsequent steps on the Queue timeline of this.

Queue timeline steps:
  1. Assert that the texel block width of destination.texture is 1, the texel block height of destination.texture is 1, and that copySize.depthOrArrayLayers is 1.

  2. Let srcOrigin be source.origin.

  3. Let dstOrigin be destination.origin.

  4. Let dstSubregion be texture copy sub-region (dstOrigin.z) of destination.

  5. For each y in the range [0, copySize.height − 1]:

    1. Let srcY be y if source.flipY is false and (copySize.height − 1 − y) otherwise.

    2. For each x in the range [0, copySize.width − 1]:

      1. Set texel block (dstOrigin.x + x, dstOrigin.y + y) of dstSubregion to be an equivalent texel representation of the pixel at (srcOrigin.x + x, srcOrigin.y + srcY) of source.source after applying any color encoding required by destination.colorSpace and destination.premultipliedAlpha.

submit(commandBuffers)

Schedules the execution of the command buffers by the GPU on this queue.

Submitted command buffers cannot be used again.

Called on: GPUQueue this.

Arguments:

Arguments for the GPUQueue.submit(commandBuffers) method.
Parameter Type Nullable Optional Description
commandBuffers sequence<GPUCommandBuffer>

Returns: undefined

Content timeline steps:

  1. Issue the subsequent steps on the Device timeline of this:

Device timeline steps:
  1. If any of the following requirements are unmet, generate a validation error, invalidate each GPUCommandBuffer in commandBuffers and return.

  2. For each commandBuffer in commandBuffers:

    1. Invalidate commandBuffer.

  3. Issue the subsequent steps on the Queue timeline of this:

Queue timeline steps:
  1. For each commandBuffer in commandBuffers:

    1. Execute each command in commandBuffer.[[command_list]].

onSubmittedWorkDone()

Returns a Promise that resolves once this queue finishes processing all the work submitted up to this moment.

Resolution of this Promise implies the completion of mapAsync() calls made prior to that call, on GPUBuffers last used exclusively on that queue.

Called on: GPUQueue this.

Returns: Promise<undefined>

Content timeline steps:

  1. Let contentTimeline be the current Content timeline.

  2. Let promise be a new promise.

  3. Issue the synchronization steps on the Device timeline of this.

  4. Return promise.

Device timeline synchronization steps:
  1. Let event occur upon the completion of all currently-enqueued operations.

  2. Listen for timeline event event on this.[[device]], handled by the subsequent steps on contentTimeline.

Content timeline steps:
  1. Resolve promise.

20. Queries

20.1. GPUQuerySet

[Exposed=(Window, Worker), SecureContext]
interface GPUQuerySet {
    undefined destroy();

    readonly attribute GPUQueryType type;
    readonly attribute GPUSize32Out count;
};
GPUQuerySet includes GPUObjectBase;

GPUQuerySet has the following immutable properties:

type, of type GPUQueryType, readonly

The type of the queries managed by this GPUQuerySet.

count, of type GPUSize32Out, readonly

The number of queries managed by this GPUQuerySet.

GPUQuerySet has the following device timeline properties:

[[destroyed]], of type boolean, initially false

If the query set is destroyed, it can no longer be used in any operation, and its underlying memory can be freed.

20.1.1. QuerySet Creation

A GPUQuerySetDescriptor specifies the options to use in creating a GPUQuerySet.

dictionary GPUQuerySetDescriptor
         : GPUObjectDescriptorBase {
    required GPUQueryType type;
    required GPUSize32 count;
};
type, of type GPUQueryType

The type of queries managed by GPUQuerySet.

count, of type GPUSize32

The number of queries managed by GPUQuerySet.

createQuerySet(descriptor)

Creates a GPUQuerySet.

Called on: GPUDevice this.

Arguments:

Arguments for the GPUDevice.createQuerySet(descriptor) method.
Parameter Type Nullable Optional Description
descriptor GPUQuerySetDescriptor Description of the GPUQuerySet to create.

Returns: GPUQuerySet

Content timeline steps:

  1. If descriptor.type is "timestamp", but "timestamp-query" is not enabled for this:

    1. Throw a TypeError.

  2. Let q be ! create a new WebGPU object(this, GPUQuerySet, descriptor).

  3. Set q.type to descriptor.type.

  4. Set q.count to descriptor.count.

  5. Issue the initialization steps on the Device timeline of this.

  6. Return q.

Device timeline initialization steps:
  1. If any of the following requirements are unmet, generate a validation error, invalidate q and return.

    • this must not be lost.

    • descriptor.count must be ≤ 4096.

  2. Create a device allocation for q where each entry in the query set is zero.

    If the allocation fails without side-effects, generate an out-of-memory error, invalidate q, and return.

Creating a GPUQuerySet which holds 32 occlusion query results.
const querySet = gpuDevice.createQuerySet({
    type: 'occlusion',
    count: 32
});

20.1.2. Query Set Destruction

An application that no longer requires a GPUQuerySet can choose to lose access to it before garbage collection by calling destroy().

GPUQuerySet has the following methods:

destroy()

Destroys the GPUQuerySet.

Called on: GPUQuerySet this.

Returns: undefined

Content timeline steps:

  1. Issue the subsequent steps on the device timeline.

Device timeline steps:
  1. Set this.[[destroyed]] to true.

20.2. QueryType

enum GPUQueryType {
    "occlusion",
    "timestamp",
};

20.3. Occlusion Query

Occlusion query is only available on render passes, to query the number of fragment samples that pass all the per-fragment tests for a set of drawing commands, including scissor, sample mask, alpha to coverage, stencil, and depth tests. Any non-zero result value for the query indicates that at least one sample passed the tests and reached the output merging stage of the render pipeline, 0 indicates that no samples passed the tests.

When beginning a render pass, GPURenderPassDescriptor.occlusionQuerySet must be set to be able to use occlusion queries during the pass. An occlusion query is begun and ended by calling beginOcclusionQuery() and endOcclusionQuery() in pairs that cannot be nested, and resolved into a GPUBuffer as a 64-bit unsigned integer by GPUCommandEncoder.resolveQuerySet().

20.4. Timestamp Query

Timestamp queries allow applications to write timestamps to a GPUQuerySet, using:

and then resolve timestamp values (in nanoseconds as a 64-bit unsigned integer) into a GPUBuffer, using GPUCommandEncoder.resolveQuerySet().

Timestamp values are implementation-defined and may not increase monotonically. The physical device may reset the timestamp counter occasionally, which can result in unexpected values such as negative deltas between timestamps that logically should be monotonically increasing. These instances should be rare and can safely be ignored. Applications should not be written in such a way that unexpected timestamps cause an application failure.

There is a tracking vector here. Timestamp queries are implemented using high-resolution timers (see § 2.1.7.2 Device/queue-timeline timing). To mitigate security and privacy concerns, their precision must be reduced:

To get the current queue timestamp, run the following queue timeline steps:

Note: Since cross-origin isolation may not apply to the device timeline or queue timeline, crossOriginIsolatedCapability is never set to true.

Validate timestampWrites(device, timestampWrites)

Arguments:

Device timeline steps:

  1. Return true if the following requirements are met, and false if not:

21. Canvas Rendering

21.1. HTMLCanvasElement.getContext()

A GPUCanvasContext object is created via the getContext() method of an HTMLCanvasElement instance by passing the string literal 'webgpu' as its contextType argument.

Get a GPUCanvasContext from an offscreen HTMLCanvasElement:
const canvas = document.createElement('canvas');
const context = canvas.getContext('webgpu');

Unlike WebGL or 2D context creation, the second argument of HTMLCanvasElement.getContext() or OffscreenCanvas.getContext(), the context creation attribute dictionary options, is ignored. Instead, use GPUCanvasContext.configure(), which allows changing the canvas configuration without replacing the canvas.

To create a 'webgpu' context on a canvas (HTMLCanvasElement or OffscreenCanvas) canvas, run the following content timeline steps:
  1. Let context be a new GPUCanvasContext.

  2. Set context.canvas to canvas.

  3. Replace the drawing buffer of context.

  4. Return context.

Note: User agents should consider issuing developer-visible warnings when an ignored options argument is provided when calling getContext() to get a WebGPU canvas context.

21.2. GPUCanvasContext

[Exposed=(Window, Worker), SecureContext]
interface GPUCanvasContext {
    readonly attribute (HTMLCanvasElement or OffscreenCanvas) canvas;

    undefined configure(GPUCanvasConfiguration configuration);
    undefined unconfigure();

    GPUCanvasConfiguration? getConfiguration();
    GPUTexture getCurrentTexture();
};

GPUCanvasContext has the following content timeline properties:

canvas, of type (HTMLCanvasElement or OffscreenCanvas), readonly

The canvas this context was created from.

[[configuration]], of type GPUCanvasConfiguration?, initially null

The options this context is currently configured with.

null if the context has not been configured or has been unconfigured.

[[textureDescriptor]], of type GPUTextureDescriptor?, initially null

The currently configured texture descriptor, derived from the [[configuration]] and canvas.

null if the context has not been configured or has been unconfigured.

[[drawingBuffer]], an image, initially a transparent black image with the same size as the canvas

The drawing buffer is the working-copy image data of the canvas. It is exposed as writable by [[currentTexture]] (returned by getCurrentTexture()).

The drawing buffer is used to get a copy of the image contents of a context, which occurs when the canvas is displayed or otherwise read. It may be transparent, even if [[configuration]].alphaMode is "opaque". The alphaMode only affects the result of the "get a copy of the image contents of a context" algorithm.

The drawing buffer outlives the [[currentTexture]] and contains the previously-rendered contents even after the canvas has been presented. It is only cleared in Replace the drawing buffer.

Any time the drawing buffer is read, implementations must ensure that all previously submitted work (e.g. queue submissions) have completed writing to it via [[currentTexture]].

[[currentTexture]], of type GPUTexture?, initially null

The GPUTexture to draw into for the current frame. It exposes a writable view onto the underlying [[drawingBuffer]]. getCurrentTexture() populates this slot if null, then returns it.

In the steady-state of a visible canvas, any changes to the drawing buffer made through the currentTexture get presented when updating the rendering of a WebGPU canvas. At or before that point, the texture is also destroyed and [[currentTexture]] is set to to null, signalling that a new one is to be created by the next call to getCurrentTexture().

Destroying the currentTexture has no effect on the drawing buffer contents; it only terminates write-access to the drawing buffer early. During the same frame, getCurrentTexture() continues returning the same destroyed texture.

Expire the current texture sets the currentTexture to null. It is called by configure(), resizing the canvas, presentation, transferToImageBitmap(), and others.

[[lastPresentedImage]], of type (readonly image)?, initially null

The image most recently presented for this canvas in "updating the rendering of a WebGPU canvas". If the device is lost or destroyed, this image may be used as a fallback in "get a copy of the image contents of a context" in order to prevent the canvas from going blank.

Note: This property only needs to exist in implementations which implement the fallback, which is optional.

GPUCanvasContext has the following methods:

configure(configuration)

Configures the context for this canvas. This clears the drawing buffer to transparent black (in Replace the drawing buffer).

Called on: GPUCanvasContext this.

Arguments:

Arguments for the GPUCanvasContext.configure(configuration) method.
Parameter Type Nullable Optional Description
configuration GPUCanvasConfiguration Desired configuration for the context.

Returns: undefined

Content timeline steps:

  1. Let device be configuration.device.

  2. ? Validate texture format required features of configuration.format with device.[[device]].

  3. ? Validate texture format required features of each element of configuration.viewFormats with device.[[device]].

  4. If Supported context formats does not contain configuration.format, throw a TypeError.

  5. Let descriptor be the GPUTextureDescriptor for the canvas and configuration(this.canvas, configuration).

  6. Set this.[[configuration]] to configuration.

    NOTE:
    This spec requires supporting HDR via the toneMapping option. If a user agent only supports toneMapping: "standard", then the toneMapping member should not exist in GPUCanvasConfiguration, so it will not exist on the object returned by getConfiguration() and will not be accessed by configure()). This allows websites to detect feature support.
  7. Set this.[[textureDescriptor]] to descriptor.

  8. Replace the drawing buffer of this.

  9. Issue the subsequent steps on the Device timeline of device.

Device timeline steps:
  1. If any of the following requirements are unmet, generate a validation error and return.

    Note: This early validation remains valid until the next configure() call, except for validation of the size, which changes when the canvas is resized.

unconfigure()

Removes the context configuration. Destroys any textures produced while configured.

Called on: GPUCanvasContext this.

Returns: undefined

Content timeline steps:

  1. Set this.[[configuration]] to null.

  2. Set this.[[textureDescriptor]] to null.

  3. Replace the drawing buffer of this.

getConfiguration()

Returns the context configuration.

Called on: GPUCanvasContext this.

Returns: GPUCanvasConfiguration or null

Content timeline steps:

  1. Let configuration be a copy of this.[[configuration]].

  2. Return configuration.

NOTE:
In scenarios where getConfiguration() shows that toneMapping is implemented and the dynamic-range media query indicates HDR support, then WebGPU canvas should render content using the full HDR range instead of clamping values to the SDR range of the HDR display.
getCurrentTexture()

Get the GPUTexture that will be composited to the document by the GPUCanvasContext next.

NOTE:
An application should call getCurrentTexture() in the same task that renders to the canvas texture. Otherwise, the texture could get destroyed by these steps before the application is finished rendering to it.

The expiry task (defined below) is optional to implement. Even if implemented, task source priority is not normatively defined, so may happen as early as the next task, or as late as after all other task sources are empty (see automatic expiry task source). Expiry is only guaranteed when a visible canvas is displayed (updating the rendering of a WebGPU canvas) and in other callers of "Expire the current texture".

Called on: GPUCanvasContext this.

Returns: GPUTexture

Content timeline steps:

  1. If this.[[configuration]] is null, throw an InvalidStateError and return.

  2. Assert this.[[textureDescriptor]] is not null.

  3. Let device be this.[[configuration]].device.

  4. If this.[[currentTexture]] is null:

    1. Replace the drawing buffer of this.

    2. Set this.[[currentTexture]] to the result of calling device.createTexture() with this.[[textureDescriptor]], except with the GPUTexture’s underlying storage pointing to this.[[drawingBuffer]].

      Note: If the texture can’t be created (e.g. due to validation failure or out-of-memory), this generates and error and returns an invalidated GPUTexture. Some validation here is redundant with that done in configure(). Implementations must not skip this redundant validation.

  5. Optionally, queue an automatic expiry task with device device and the following steps:

    1. Expire the current texture of this.

      Note: If this already happened when updating the rendering of a WebGPU canvas, it has no effect.

  6. Return this.[[currentTexture]].

Note: The same GPUTexture object will be returned by every call to getCurrentTexture() until "Expire the current texture" runs, even if that GPUTexture is destroyed, failed validation, or failed to allocate.

To get a copy of the image contents of a context:

Arguments:

Returns: image contents

Content timeline steps:

  1. Let snapshot be a transparent black image of the same size as context.canvas.

  2. Let configuration be context.[[configuration]].

  3. If configuration is null:

    1. Return snapshot.

    Note: The configuration will be null if the context has not been configured or has been unconfigured. This is identical to the behavior when the canvas has no context.

  4. Ensure that all submitted work items (e.g. queue submissions) have completed writing to the image (via context.[[currentTexture]]).

  5. If configuration.device is found to be valid:

    1. Set snapshot to a copy of the context.[[drawingBuffer]].

    Else, if context.[[lastPresentedImage]] is not null:

    1. Optionally, set snapshot to a copy of context.[[lastPresentedImage]].

      Note: This is optional because the [[lastPresentedImage]] may no longer exist, depending on what caused device loss. Implementations may choose to skip it even if do they still have access to that image.

  6. Let alphaMode be configuration.alphaMode.

  7. If alphaMode is "opaque":
    1. Clear the alpha channel of snapshot to 1.0.

    2. Tag snapshot as being opaque.

    Note: If the [[currentTexture]], if any, has been destroyed (for example in "Expire the current texture"), the alpha channel is unobservable, and implementations may clear the alpha channel in-place.

    Otherwise:

    Tag snapshot with alphaMode.

  8. Tag snapshot with the colorSpace and toneMapping of configuration.

  9. Return snapshot.

To Replace the drawing buffer of a GPUCanvasContext context, run the following content timeline steps:
  1. Expire the current texture of context.

  2. Let configuration be context.[[configuration]].

  3. Set context.[[drawingBuffer]] to a transparent black image of the same size as context.canvas.

    • If configuration is null, the drawing buffer is tagged with the color space "srgb". In this case, the drawing buffer will remain blank until the context is configured.

    • If not, the drawing buffer has the specified configuration.format and is tagged with the specified configuration.colorSpace and configuration.toneMapping.

    Note: configuration.alphaMode is ignored until "get a copy of the image contents of a context".

    NOTE:
    A newly replaced drawing buffer image behaves as if it is cleared to transparent black, but, like after "discard", an implementation can clear it lazily only if it becomes necessary.

    Note: This will often be a no-op, if the drawing buffer is already cleared and has the correct configuration.

To Expire the current texture of a GPUCanvasContext context, run the following content timeline steps:
  1. If context.[[currentTexture]] is not null:

    1. Call context.[[currentTexture]].destroy() (without destroying context.[[drawingBuffer]]) to terminate write access to the image.

    2. Set context.[[currentTexture]] to null.

21.3. HTML Specification Hooks

The following algorithms "hook" into algorithms in the HTML specification, and must run at the specified points.

When the "bitmap" is read from an HTMLCanvasElement or OffscreenCanvas with a GPUCanvasContext context, run the following content timeline steps:
  1. Return a copy of the image contents of context.

NOTE:
This occurs in many places, including:

If alphaMode is "opaque", this incurs a clear of the alpha channel. Implementations may skip this step when they are able to read or display images in a way that ignores the alpha channel.

If an application needs a canvas only for interop (not presentation), avoid "opaque" if it is not needed.

When updating the rendering of a WebGPU canvas (an HTMLCanvasElement or an OffscreenCanvas with a placeholder canvas element) with a GPUCanvasContext context, which occurs before getting the canvas’s image contents, in the following sub-steps of the event loop processing model:

Note: Service and Shared workers do not have "update the rendering" steps because they cannot render to user-visible canvases. requestAnimationFrame() is not exposed in ServiceWorkerGlobalScope and SharedWorkerGlobalScope, and OffscreenCanvases from transferControlToOffscreen() cannot be sent to these workers.

Run the following content timeline steps:

  1. Expire the current texture of context.

    Note: If this already happened in the task queued by getCurrentTexture(), it has no effect.

  2. Set context.[[lastPresentedImage]] to context.[[drawingBuffer]].

    Note: This is just a reference, not a copy; the drawing buffer’s contents can’t change in-place after the current texture has expired.

Note: This does not happen for standalone OffscreenCanvases (created by new OffscreenCanvas()).

transferToImageBitmap from WebGPU:

When transferToImageBitmap() is called on a canvas with GPUCanvasContext context, after creating an ImageBitmap from the canvas’s bitmap, run the following content timeline steps:

  1. Replace the drawing buffer of context.

Note: This makes transferToImageBitmap() equivalent to "moving" (and possibly alpha-clearing) the image contents into the ImageBitmap, without a copy.

21.4. GPUCanvasConfiguration

The supported context formats are the set of GPUTextureFormats: «"bgra8unorm", "rgba8unorm", "rgba16float"». These formats must be supported when specified as a GPUCanvasConfiguration.format regardless of the given GPUCanvasConfiguration.device.

Note: Canvas configuration cannot use srgb formats like "bgra8unorm-srgb". Instead, use the non-srgb equivalent ("bgra8unorm"), specify the srgb format in the viewFormats, and use createView() to create a view with an srgb format.

enum GPUCanvasAlphaMode {
    "opaque",
    "premultiplied",
};

enum GPUCanvasToneMappingMode {
    "standard",
    "extended",
};

dictionary GPUCanvasToneMapping {
  GPUCanvasToneMappingMode mode = "standard";
};

dictionary GPUCanvasConfiguration {
    required GPUDevice device;
    required GPUTextureFormat format;
    GPUTextureUsageFlags usage = 0x10;  // GPUTextureUsage.RENDER_ATTACHMENT
    sequence<GPUTextureFormat> viewFormats = [];
    PredefinedColorSpace colorSpace = "srgb";
    GPUCanvasToneMapping toneMapping = {};
    GPUCanvasAlphaMode alphaMode = "opaque";
};

GPUCanvasConfiguration has the following members:

device, of type GPUDevice

The GPUDevice that textures returned by getCurrentTexture() will be compatible with.

format, of type GPUTextureFormat

The format that textures returned by getCurrentTexture() will have. Must be one of the Supported context formats.

usage, of type GPUTextureUsageFlags, defaulting to 0x10

The usage that textures returned by getCurrentTexture() will have. RENDER_ATTACHMENT is the default, but is not automatically included if the usage is explicitly set. Be sure to include RENDER_ATTACHMENT when setting a custom usage if you wish to use textures returned by getCurrentTexture() as color targets for a render pass.

viewFormats, of type sequence<GPUTextureFormat>, defaulting to []

The formats that views created from textures returned by getCurrentTexture() may use.

colorSpace, of type PredefinedColorSpace, defaulting to "srgb"

The color space that values written into textures returned by getCurrentTexture() should be displayed with.

toneMapping, of type GPUCanvasToneMapping, defaulting to {}

The tone mapping determines how the content of textures returned by getCurrentTexture() are to be displayed.

Note: If an implementation doesn’t support HDR WebGPU canvases, it should also not expose this member, to allow for feature detection. See getConfiguration().

alphaMode, of type GPUCanvasAlphaMode, defaulting to "opaque"

Determines the effect that alpha values will have on the content of textures returned by getCurrentTexture() when read, displayed, or used as an image source.

Configure a GPUCanvasContext to be used with a specific GPUDevice, using the preferred format for this context:
const canvas = document.createElement('canvas');
const context = canvas.getContext('webgpu');

context.configure({
    device: gpuDevice,
    format: navigator.gpu.getPreferredCanvasFormat(),
});
The GPUTextureDescriptor for the canvas and configuration( (HTMLCanvasElement or OffscreenCanvas) canvas, GPUCanvasConfiguration configuration) is a GPUTextureDescriptor with the following members:

and other members set to their defaults.

canvas.width refers to HTMLCanvasElement.width or OffscreenCanvas.width. canvas.height refers to HTMLCanvasElement.height or OffscreenCanvas.height.

21.4.1. Canvas Color Space

During presentation, the color values in the canvas are converted to the color space of the screen.

The toneMapping determines the handling of values outside of the [0, 1] interval in the color space of the screen.

21.4.2. Canvas Context sizing

All canvas configuration is set in configure() except for the resolution of the canvas, which is set by the canvas’s width and height.

Note: Like WebGL and 2d canvas, resizing a WebGPU canvas loses the current contents of the drawing buffer. In WebGPU, it does so by replacing the drawing buffer.

When an HTMLCanvasElement or OffscreenCanvas canvas with a GPUCanvasContext context has its width or height attributes set, update the canvas size by running the following content timeline steps:
  1. Replace the drawing buffer of context.

  2. Let configuration be context.[[configuration]]

  3. If configuration is not null:

    1. Set context.[[textureDescriptor]] to the GPUTextureDescriptor for the canvas and configuration(canvas, configuration).

Note: This may result in a GPUTextureDescriptor which exceeds the maxTextureDimension2D of the device. In this case, validation will fail inside getCurrentTexture().

Note: This algorithm is run any time the canvas width or height attributes are set, even if their value is not changed.

21.5. GPUCanvasToneMappingMode

This enum specifies how color values are displayed to the screen.

"standard"

Color values within the standard dynamic range of the screen are unchanged, and all other color values are projected to the standard dynamic range of the screen.

Note: This projection is often accomplished by clamping color values in the color space of the screen to the [0, 1] interval.

For example, suppose that the value (1.035, -0.175, -0.140) is written to an 'srgb' canvas.

If this is presented to an sRGB screen, then this will be converted to sRGB (which is a no-op, because the canvas is sRGB), then projected into the display’s space. Using component-wise clamping, this results in the sRGB value (1.0, 0.0, 0.0).

If this is presented to a Display P3 screen, then this will be converted to the value (0.948, 0.106, 0.01) in the Display P3 color space, and no clamping will be needed.

"extended"

Color values in the extended dynamic range of the screen are unchanged, and all other color values are projected to the extended dynamic range of the screen.

Note: This projection is often accomplished by clamping color values in the color space of the screen to the interval of values that the screen is capable of displaying, which may include values greater than 1.

For example, suppose that the value (2.5, -0.15, -0.15) is written to an 'srgb' canvas.

If this is presented to an sRGB screen that is capable of displaying values in the [0, 4] interval in sRGB space, then this will be converted to sRGB (which is a no-op, because the canvas is sRGB), then projected into the display’s space. If using component-wise clamping, this results in the sRGB value (2.5, 0.0, 0.0).

If this is presented to a Display P3 screen that is capable of displaying values in the [0, 2] interval in Display P3 space, then this will be converted to the value (2.3, 0.545, 0.386) in the Display P3 color space, then projected into the display’s space. If using component-wise clamping, this results in the Display P3 value (2.0, 0.545, 0.386).

21.6. GPUCanvasAlphaMode

This enum selects how the contents of the canvas will be interpreted when read, when displayed to the screen or used as an image source (in drawImage, toDataURL, etc.)

Below, src is a value in the canvas texture, and dst is an image that the canvas is being composited into (e.g. an HTML page rendering, or a 2D canvas).

"opaque"

Read RGB as opaque and ignore alpha values. If the content is not already opaque, the alpha channel is cleared to 1.0 in "get a copy of the image contents of a context".

"premultiplied"

Read RGBA as premultiplied: color values are premultiplied by their alpha value. 100% red at 50% alpha is [0.5, 0, 0, 0.5].

If the canvas texture contains out-of-gamut premultiplied RGBA values at the time the canvas contents are read, the behavior depends on whether the canvas is:

used as an image source

Values are preserved, as described in color space conversion.

displayed to the screen

Compositing results are undefined.

Note: This is true even if color space conversion would produce in-gamut values before compositing, because the intermediate format for compositing is not specified.

22. Errors & Debugging

During the normal course of operation of WebGPU, errors are raised via dispatch error.

After a device is lost, errors are no longer surfaced, where possible. After this point, implementations do not need to run validation or error tracking:

22.1. Fatal Errors

enum GPUDeviceLostReason {
    "unknown",
    "destroyed",
};

[Exposed=(Window, Worker), SecureContext]
interface GPUDeviceLostInfo {
    readonly attribute GPUDeviceLostReason reason;
    readonly attribute DOMString message;
};

partial interface GPUDevice {
    readonly attribute Promise<GPUDeviceLostInfo> lost;
};

GPUDevice has the following additional attributes:

lost, of type Promise<GPUDeviceLostInfo>, readonly

A slot-backed attribute holding a promise which is created with the device, remains pending for the lifetime of the device, then resolves when the device is lost.

Upon initialization, it is set to a new promise.

22.2. GPUError

[Exposed=(Window, Worker), SecureContext]
interface GPUError {
    readonly attribute DOMString message;
};

GPUError is the base interface for all errors surfaced from popErrorScope() and the uncapturederror event.

Errors must only be generated for operations that explicitly state the conditions one may be generated under in their respective algorithms, and the subtype of error that is generated.

No errors are generated from a device which is lost. See § 22 Errors & Debugging.

Note: GPUError may gain new subtypes in future versions of this spec. Applications should handle this possibility, using only the error’s message when possible, and specializing using instanceof. Use error.constructor.name when it’s necessary to serialize an error (e.g. into JSON, for a debug report).

GPUError has the following immutable properties:

message, of type DOMString, readonly

A human-readable, localizable text message providing information about the error that occurred.

Note: This message is generally intended for application developers to debug their applications and capture information for debug reports, not to be surfaced to end-users.

Note: User agents should not include potentially machine-parsable details in this message, such as free system memory on "out-of-memory" or other details about the conditions under which memory was exhausted.

Note: The message should follow the best practices for language and direction information. This includes making use of any future standards which may emerge regarding the reporting of string language and direction metadata.

Editorial note: At the time of this writing, no language/direction recommendation is available that provides compatibility and consistency with legacy APIs, but when there is, adopt it formally.

[Exposed=(Window, Worker), SecureContext]
interface GPUValidationError
        : GPUError {
    constructor(DOMString message);
};

GPUValidationError is a subtype of GPUError which indicates that an operation did not satisfy all validation requirements. Validation errors are always indicative of an application error, and is expected to fail the same way across all devices assuming the same [[features]] and [[limits]] are in use.

To generate a validation error for GPUDevice device, run the following steps:

Device timeline steps:

  1. Let error be a new GPUValidationError with an appropriate error message.

  2. Dispatch error error to device.

[Exposed=(Window, Worker), SecureContext]
interface GPUOutOfMemoryError
        : GPUError {
    constructor(DOMString message);
};

GPUOutOfMemoryError is a subtype of GPUError which indicates that there was not enough free memory to complete the requested operation. The operation may succeed if attempted again with a lower memory requirement (like using smaller texture dimensions), or if memory used by other resources is released first.

To generate an out-of-memory error for GPUDevice device, run the following steps:

Device timeline steps:

  1. Let error be a new GPUOutOfMemoryError with an appropriate error message.

  2. Dispatch error error to device.

[Exposed=(Window, Worker), SecureContext]
interface GPUInternalError
        : GPUError {
    constructor(DOMString message);
};

GPUInternalError is a subtype of GPUError which indicates than an operation failed for a system or implementation-specific reason even when all validation requirements have been satisfied. For example, the operation may exceed the capabilities of the implementation in a way not easily captured by the supported limits. The same operation may succeed on other devices or under difference circumstances.

To generate an internal error for GPUDevice device, run the following steps:

Device timeline steps:

  1. Let error be a new GPUInternalError with an appropriate error message.

  2. Dispatch error error to device.

22.3. Error Scopes

A GPU error scope captures GPUErrors that were generated while the GPU error scope was current. Error scopes are used to isolate errors that occur within a set of WebGPU calls, typically for debugging purposes or to make an operation more fault tolerant.

GPU error scope has the following device timeline properties:

[[errors]], of type list<GPUError>, initially []

The GPUErrors, if any, observed while the GPU error scope was current.

[[filter]], of type GPUErrorFilter

Determines what type of GPUError this GPU error scope observes.

enum GPUErrorFilter {
    "validation",
    "out-of-memory",
    "internal",
};

partial interface GPUDevice {
    undefined pushErrorScope(GPUErrorFilter filter);
    Promise<GPUError?> popErrorScope();
};

GPUErrorFilter defines the type of errors that should be caught when calling pushErrorScope():

"validation"

Indicates that the error scope will catch a GPUValidationError.

"out-of-memory"

Indicates that the error scope will catch a GPUOutOfMemoryError.

"internal"

Indicates that the error scope will catch a GPUInternalError.

GPUDevice has the following device timeline properties:

[[errorScopeStack]], of type stack<GPU error scope>

A stack of GPU error scopes that have been pushed to the GPUDevice.

The current error scope for a GPUError error and GPUDevice device is determined by issuing the following steps to the device timeline of device:

Device timeline steps:

  1. If error is an instance of:

    GPUValidationError

    Let type be "validation".

    GPUOutOfMemoryError

    Let type be "out-of-memory".

    GPUInternalError

    Let type be "internal".

  2. Let scope be the last item of device.[[errorScopeStack]].

  3. While scope is not undefined:

    1. If scope.[[filter]] is type, return scope.

    2. Set scope to the previous item of device.[[errorScopeStack]].

  4. Return undefined.

To dispatch an error GPUError error on GPUDevice device, run the following device timeline steps:
Device timeline steps:

Note: No errors are generated from a device which is lost. If this algorithm is called while device is lost, it will not be observable to the application. See § 22 Errors & Debugging.

  1. Let scope be the current error scope for error and device.

  2. If scope is not undefined:

    1. Append error to scope.[[errors]].

    2. Return.

  3. Otherwise issue the following steps to the content timeline:

Content timeline steps:
  1. If the user agent chooses, queue a global task for GPUDevice device with the following steps:

    1. Fire a GPUUncapturedErrorEvent named "uncapturederror" on device, with an error of error.

Note: After dispatching the event, user agents should surface uncaptured errors to developers, for example as warnings in the browser’s developer console, unless the event’s defaultPrevented is true. In other words, calling preventDefault() on the event should silence the console warning.

Note: The user agent may choose to throttle or limit the number of GPUUncapturedErrorEvents that a GPUDevice can raise to prevent an excessive amount of error handling or logging from impacting performance.

pushErrorScope(filter)

Pushes a new GPU error scope onto the [[errorScopeStack]] for this.

Called on: GPUDevice this.

Arguments:

Arguments for the GPUDevice.pushErrorScope(filter) method.
Parameter Type Nullable Optional Description
filter GPUErrorFilter Which class of errors this error scope observes.

Returns: undefined

Content timeline steps:

  1. Issue the subsequent steps on the Device timeline of this.

Device timeline steps:
  1. Let scope be a new GPU error scope.

  2. Set scope.[[filter]] to filter.

  3. Push scope onto this.[[errorScopeStack]].

popErrorScope()

Pops a GPU error scope off the [[errorScopeStack]] for this and resolves to any GPUError observed by the error scope, or null if none.

There is no guarantee of the ordering of promise resolution.

Called on: GPUDevice this.

Returns: Promise<GPUError?>

Content timeline steps:

  1. Let contentTimeline be the current Content timeline.

  2. Let promise be a new promise.

  3. Issue the check steps on the Device timeline of this.

  4. Return promise.

Device timeline check steps:
  1. If this is lost:

    1. Issue the following steps on contentTimeline:

      Content timeline steps:
      1. Resolve promise with null.

    2. Return.

    Note: No errors are generated from a device which is lost. See § 22 Errors & Debugging.

  2. If any of the following requirements are unmet:

    Then issue the following steps on contentTimeline and return:

    Content timeline steps:
    1. Reject promise with an OperationError.

  3. Let scope be the result of popping an item off of this.[[errorScopeStack]].

  4. Let error be any one of the items in scope.[[errors]], or null if there are none.

    For any two errors E1 and E2 in the list, if E2 was caused by E1, E2 should not be the one selected.

    Note: For example, if E1 comes from t = createTexture(), and E2 comes from t.createView() because t was invalid, E1 should be be preferred since it will be easier for a developer to understand what went wrong. Since both of these are GPUValidationErrors, the only difference will be in the message field, which is meant only to be read by humans anyway.

  5. At an unspecified point now or in the future, issue the subsequent steps on contentTimeline.

    Note: By allowing popErrorScope() calls to resolve in any order, with any of the errors observed by the scope, this spec allows validation to complete out of order, as long as any state observations are made at the appropriate point in adherence to this spec. For example, this allows implementations to perform shader compilation, which depends only on non-stateful inputs, to be completed on a background thread in parallel with other device-timeline work, and report any resulting errors later.

Content timeline steps:
  1. Resolve promise with error.

Using error scopes to capture validation errors from a GPUDevice operation that may fail:
gpuDevice.pushErrorScope('validation');

let sampler = gpuDevice.createSampler({
    maxAnisotropy: 0, // Invalid, maxAnisotropy must be at least 1.
});

gpuDevice.popErrorScope().then((error) => {
    if (error) {
        // There was an error creating the sampler, so discard it.
        sampler = null;
        console.error(`An error occured while creating sampler: ${error.message}`);
    }
});
NOTE:
Error scopes can encompass as many commands as needed. The number of commands an error scope covers will generally be correlated to what sort of action the application intends to take in response to an error occuring.

For example: An error scope that only contains the creation of a single resource, such as a texture or buffer, can be used to detect failures such as out of memory conditions, in which case the application may try freeing some resources and trying the allocation again.

Error scopes do not identify which command failed, however. So, for instance, wrapping all the commands executed while loading a model in a single error scope will not offer enough granularity to determine if the issue was due to memory constraints. As a result freeing resources would usually not be a productive response to a failure of that scope. A more appropriate response would be to allow the application to fall back to a different model or produce a warning that the model could not be loaded. If responding to memory constraints is desired, the operations allocating memory can always be wrapped in a smaller nested error scope.

22.4. Telemetry

When a GPUError is generated that is not observed by any GPU error scope, the user agent may fire an event named uncapturederror at a GPUDevice using GPUUncapturedErrorEvent.

Note: uncapturederror events are intended to be used for telemetry and reporting unexpected errors. They may not be dispatched for all uncaptured errors (for example, there may be a limit on the number of errors surfaced), and should not be used for handling known error cases that may occur during normal operation of an application. Prefer using pushErrorScope() and popErrorScope() in those cases.

[Exposed=(Window, Worker), SecureContext]
interface GPUUncapturedErrorEvent : Event {
    constructor(
        DOMString type,
        GPUUncapturedErrorEventInit gpuUncapturedErrorEventInitDict
    );
    [SameObject] readonly attribute GPUError error;
};

dictionary GPUUncapturedErrorEventInit : EventInit {
    required GPUError error;
};

GPUUncapturedErrorEvent has the following attributes:

error, of type GPUError, readonly

A slot-backed attribute holding an object representing the error that was uncaptured. This has the same type as errors returned by popErrorScope().

partial interface GPUDevice {
    attribute EventHandler onuncapturederror;
};

GPUDevice has the following content timeline properties:

onuncapturederror, of type EventHandler

An event handler IDL attribute for the uncapturederror event type.

Listening for uncaptured errors from a GPUDevice:
gpuDevice.addEventListener('uncapturederror', (event) => {
    // Re-surface the error, because adding an event listener may silence console logs.
    console.error('A WebGPU error was not captured:', event.error);

    myEngineDebugReport.uncapturedErrors.push({
        type: event.error.constructor.name,
        message: event.error.message,
    });
});

23. Detailed Operations

This section describes the details of various GPU operations.

23.1. Computing

Computing operations provide direct access to GPU’s programmable hardware. Compute shaders do not have shader stage inputs or outputs; their results are side effects from writing data into storage bindings bound either as GPUBufferBindingLayout with GPUBufferBindingType "storage" or as GPUStorageTextureBindingLayout. These operations are encoded within GPUComputePassEncoder as:

The main compute algorithm:

compute(descriptor, drawCall, state)

Arguments:

  1. Let computeInvocations be an empty list.

  2. Let computeStage be descriptor.compute.

  3. Let workgroupSize be the computed workgroup size for computeStage.entryPoint after applying computeStage.constants to computeStage.module.

  4. For workgroupX in range [0, dispatchCall.workgroupCountX]:

    1. For workgroupY in range [0, dispatchCall.workgroupCountY]:

      1. For workgroupZ in range [0, dispatchCall.workgroupCountZ]:

        1. For localX in range [0, workgroupSize.x]:

          1. For localY in range [0, workgroupSize.y]:

            1. For localZ in range [0, workgroupSize.y]:

              1. Let invocation be { computeStage, workgroupX, workgroupY, workgroupZ, localX, localY, localZ }

              2. Append invocation to computeInvocations.

  5. For every invocation in computeInvocations, in any order the device chooses, including in parallel:

    1. Set the shader builtins:

      • Set the num_workgroups builtin, if any, to (
        dispatchCall.workgroupCountX,
        dispatchCall.workgroupCountY,
        dispatchCall.workgroupCountZ
        )

      • Set the workgroup_id builtin, if any, to (
        invocation.workgroupX,
        invocation.workgroupY,
        invocation.workgroupZ
        )

      • Set the local_invocation_id builtin, if any, to (
        invocation.localX,
        invocation.localY,
        invocation.localZ
        )

      • Set the global_invocation_id builtin, if any, to (
        invocation.workgroupX * workgroupSize.x + invocation.localX,
        invocation.workgroupY * workgroupSize.y + invocation.localY,
        invocation.workgroupZ * workgroupSize.z + invocation.localZ
        )
        .

      • Set the local_invocation_index builtin, if any, to invocation.localX + (invocation.localY * workgroupSize.x) + (invocation.localZ * workgroupSize.x * workgroupSize.y)

    2. Invoke the compute shader entry point described by invocation.computeStage.

Note: Shader invocations have no guaranteed order, and will generally run in parallel according to device capabilities. Developers should not assume that any given invocation or workgroup will complete before any other one is started. Some devices may appear to execute in a consistent order, but this behavior should not be relied on as it will not perform identically across all devices. Shaders that require synchronization across invocations must use Synchronization Built-in Functions to coordinate execution.

The device may become lost if shader execution does not end in a reasonable amount of time, as determined by the user agent.

23.2. Rendering

Rendering is done by a set of GPU operations that are executed within GPURenderPassEncoder, and result in modifications of the texture data, viewed by the render pass attachments. These operations are encoded with:

Note: rendering is the traditional use of GPUs, and is supported by multiple fixed-function blocks in hardware.

The main rendering algorithm:

render(pipeline, drawCall, state)

Arguments:

  1. Let descriptor be pipeline.[[descriptor]].

  2. Resolve indices. See § 23.2.1 Index Resolution.

    Let vertexList be the result of resolve indices(drawCall, state).

  3. Process vertices. See § 23.2.2 Vertex Processing.

    Execute process vertices(vertexList, drawCall, descriptor.vertex, state).

  4. Assemble primitives. See § 23.2.3 Primitive Assembly.

    Execute assemble primitives(vertexList, drawCall, descriptor.primitive).

  5. Clip primitives. See § 23.2.4 Primitive Clipping.

    Let primitiveList be the result of this stage.

  6. Rasterize. See § 23.2.5 Rasterization.

    Let rasterizationList be the result of rasterize(primitiveList, state).

  7. Process fragments. See § 23.2.6 Fragment Processing.

    Gather a list of fragments, resulting from executing process fragment(rasterPoint, descriptor, state) for each rasterPoint in rasterizationList.

  8. Write pixels. See § 23.2.7 Output Merging.

    For each non-null fragment of fragments:

23.2.1. Index Resolution

At the first stage of rendering, the pipeline builds a list of vertices to process for each instance.

resolve indices(drawCall, state)

Arguments:

Returns: list of integer indices.

  1. Let vertexIndexList be an empty list of indices.

  2. If drawCall is an indexed draw call:

    1. Initialize the vertexIndexList with drawCall.indexCount integers.

    2. For i in range 0 .. drawCall.indexCount (non-inclusive):

      1. Let relativeVertexIndex be fetch index(i + drawCall.firstIndex, state.[[index_buffer]]).

      2. If relativeVertexIndex has the special value "out of bounds", return the empty list.

        Note: Implementations may choose to display a warning when this occurs, especially when it is easy to detect (like in non-indirect indexed draw calls).

      3. Append drawCall.baseVertex + relativeVertexIndex to the vertexIndexList.

  3. Otherwise:

    1. Initialize the vertexIndexList with drawCall.vertexCount integers.

    2. Set each vertexIndexList item i to the value drawCall.firstVertex + i.

  4. Return vertexIndexList.

Note: in the case of indirect draw calls, the indexCount, vertexCount, and other properties of drawCall are read from the indirect buffer instead of the draw command itself.

fetch index(i, buffer, offset, format)

Arguments:

Returns: unsigned integer or "out of bounds"

  1. Let indexSize be defined by the state.[[index_format]]:

    "uint16"

    2

    "uint32"

    4

  2. If state.[[index_buffer_offset]] + |i + 1| × indexSize > state.[[index_buffer_size]], return the special value "out of bounds".

  3. Interpret the data in state.[[index_buffer]], starting at offset state.[[index_buffer_offset]] + i × indexSize, of size indexSize bytes, as an unsigned integer and return it.

23.2.2. Vertex Processing

Vertex processing stage is a programmable stage of the render pipeline that processes the vertex attribute data, and produces clip space positions for § 23.2.4 Primitive Clipping, as well as other data for the § 23.2.6 Fragment Processing.

process vertices(vertexIndexList, drawCall, desc, state)

Arguments:

Each vertex vertexIndex in the vertexIndexList, in each instance of index rawInstanceIndex, is processed independently. The rawInstanceIndex is in range from 0 to drawCall.instanceCount - 1, inclusive. This processing happens in parallel, and any side effects, such as writes into GPUBufferBindingType "storage" bindings, may happen in any order.

  1. Let instanceIndex be rawInstanceIndex + drawCall.firstInstance.

  2. For each non-null vertexBufferLayout in the list of desc.buffers:

    1. Let i be the index of the buffer layout in this list.

    2. Let vertexBuffer, vertexBufferOffset, and vertexBufferBindingSize be the buffer, offset, and size at slot i of state.[[vertex_buffers]].

    3. Let vertexElementIndex be dependent on vertexBufferLayout.stepMode:

      "vertex"

      vertexIndex

      "instance"

      instanceIndex

    4. Let drawCallOutOfBounds be false.

    5. For each attributeDesc in vertexBufferLayout.attributes:

      1. Let attributeOffset be vertexBufferOffset + vertexElementIndex * vertexBufferLayout.arrayStride + attributeDesc.offset.

      2. If attributeOffset + byteSize(attributeDesc.format) > vertexBufferOffset + vertexBufferBindingSize:

        1. Set drawCallOutOfBounds to true.

        2. Optionally (implementation-defined), empty vertexIndexList and return, cancelling the draw call.

          Note: This allows implementations to detect out-of-bounds values in the index buffer before issuing a draw call, instead of using invalid memory reference behavior.

    6. For each attributeDesc in vertexBufferLayout.attributes:

      1. If drawCallOutOfBounds is true:

        1. Load the attribute data according to WGSL’s invalid memory reference behavior, from vertexBuffer.

          Note: Invalid memory reference allows several behaviors, including actually loading the "correct" result for an attribute that is in-bounds, even when the draw-call-wide drawCallOutOfBounds is true.

        Otherwise:

        1. Let attributeOffset be vertexBufferOffset + vertexElementIndex * vertexBufferLayout.arrayStride + attributeDesc.offset.

        2. Load the attribute data of format attributeDesc.format from vertexBuffer starting at offset attributeOffset. The components are loaded in the order x, y, z, w from buffer memory.

      2. Convert the data into a shader-visible format, according to channel formats rules.

        An attribute of type "snorm8x2" and byte values of [0x70, 0xD0] will be converted to vec2<f32>(0.88, -0.38) in WGSL.
      3. Adjust the data size to the shader type:

        • if both are scalar, or both are vectors of the same dimensionality, no adjustment is needed.

        • if data is vector but the shader type is scalar, then only the first component is extracted.

        • if both are vectors, and data has a higher dimension, the extra components are dropped.

          An attribute of type "float32x3" and value vec3<f32>(1.0, 2.0, 3.0) will exposed to the shader as vec2<f32>(1.0, 2.0) if a 2-component vector is expected.
        • if the shader type is a vector of higher dimensionality, or the data is a scalar, then the missing components are filled from vec4<*>(0, 0, 0, 1) value.

          An attribute of type "sint32" and value 5 will be exposed to the shader as vec4<i32>(5, 0, 0, 1) if a 4-component vector is expected.
      4. Bind the data to vertex shader input location attributeDesc.shaderLocation.

  3. For each GPUBindGroup group at index in state.[[bind_groups]]:

    1. For each resource GPUBindingResource in the bind group:

      1. Let entry be the corresponding GPUBindGroupLayoutEntry for this resource.

      2. If entry.visibility includes VERTEX:

  4. Set the shader builtins:

    • Set the vertex_index builtin, if any, to vertexIndex.

    • Set the instance_index builtin, if any, to instanceIndex.

  5. Invoke the vertex shader entry point described by desc.

    Note: The target platform caches the results of vertex shader invocations. There is no guarantee that any vertexIndex that repeats more than once will result in multiple invocations. Similarly, there is no guarantee that a single vertexIndex will only be processed once.

    The device may become lost if shader execution does not end in a reasonable amount of time, as determined by the user agent.

23.2.3. Primitive Assembly

Primitives are assembled by a fixed-function stage of GPUs.

assemble primitives(vertexIndexList, drawCall, desc)

Arguments:

For each instance, the primitives get assembled from the vertices that have been processed by the shaders, based on the vertexIndexList.

  1. First, if the primitive topology is a strip, (which means that desc.stripIndexFormat is not undefined) and the drawCall is indexed, the vertexIndexList is split into sub-lists using the maximum value of desc.stripIndexFormat as a separator.

    Example: a vertexIndexList with values [1, 2, 65535, 4, 5, 6] of type "uint16" will be split in sub-lists [1, 2] and [4, 5, 6].

  2. For each of the sub-lists vl, primitive generation is done according to the desc.topology:

    "line-list"

    Line primitives are composed from (vl.0, vl.1), then (vl.2, vl.3), then (vl.4 to vl.5), etc. Each subsequent primitive takes 2 vertices.

    "line-strip"

    Line primitives are composed from (vl.0, vl.1), then (vl.1, vl.2), then (vl.2, vl.3), etc. Each subsequent primitive takes 1 vertex.

    "triangle-list"

    Triangle primitives are composed from (vl.0, vl.1, vl.2), then (vl.3, vl.4, vl.5), then (vl.6, vl.7, vl.8), etc. Each subsequent primitive takes 3 vertices.

    "triangle-strip"

    Triangle primitives are composed from (vl.0, vl.1, vl.2), then (vl.2, vl.1, vl.3), then (vl.2, vl.3, vl.4), then (vl.4, vl.3, vl.5), etc. Each subsequent primitive takes 1 vertices.

    Any incomplete primitives are dropped.

23.2.4. Primitive Clipping

Vertex shaders have to produce a built-in position (of type vec4<f32>), which denotes the clip position of a vertex in clip space coordinates.

Primitives are clipped to the clip volume, which, for any clip position p inside a primitive, is defined by the following inequalities:

When the "clip-distances" feature is enabled, this clip volume can be further restricted by user-defined half-spaces by declaring clip_distances in the output of vertex stage. Each value in the clip_distances array will be linearly interpolated across the primitive, and the portion of the primitive with interpolated distances less than 0 will be clipped.

If descriptor.primitive.unclippedDepth is true, depth clipping is not applied: the clip volume is not bounded in the z dimension.

A primitive passes through this stage unchanged if every one of its edges lie entirely inside the clip volume. If the edges of a primitives intersect the boundary of the clip volume, the intersecting edges are reconnected by new edges that lie along the boundary of the clip volume. For triangular primitives (descriptor.primitive.topology is "triangle-list" or "triangle-strip"), this reconnection may result in introduction of new vertices into the polygon, internally.

If a primitive intersects an edge of the clip volume’s boundary, the clipped polygon must include a point on this boundary edge.

If the vertex shader outputs other floating-point values (scalars and vectors), qualified with "perspective" interpolation, they also get clipped. The output values associated with a vertex that lies within the clip volume are unaffected by clipping. If a primitive is clipped, however, the output values assigned to vertices produced by clipping are clipped.

Considering an edge between vertices a and b that got clipped, resulting in the vertex c, let’s define t to be the ratio between the edge vertices: c.p = t × a.p + (1 − t) × b.p, where x.p is the output clip position of a vertex x.

For each vertex output value "v" with a corresponding fragment input, a.v and b.v would be the outputs for a and b vertices respectively. The clipped shader output c.v is produced based on the interpolation qualifier:

flat

Flat interpolation is unaffected, and is based on the provoking vertex, which is determined by the interpolation sampling mode declared in the shader. The output value is the same for the whole primitive, and matches the vertex output of the provoking vertex.

linear

The interpolation ratio gets adjusted against the perspective coordinates of the clip positions, so that the result of interpolation is linear in screen space.

perspective

The value is linearly interpolated in clip space, producing perspective-correct values.

The result of primitive clipping is a new set of primitives, which are contained within the clip volume.

23.2.5. Rasterization

Rasterization is the hardware processing stage that maps the generated primitives to the 2-dimensional rendering area of the framebuffer - the set of render attachments in the current GPURenderPassEncoder. This rendering area is split into an even grid of pixels.

The framebuffer coordinates start from the top-left corner of the render targets. Each unit corresponds exactly to one pixel. See § 3.3 Coordinate Systems for more information.

Rasterization determines the set of pixels affected by a primitive. In case of multi-sampling, each pixel is further split into descriptor.multisample.count samples. The standard sample patterns are as follows, with positions in framebuffer coordinates relative to the top-left corner of the pixel, such that the pixel ranges from (0, 0) to (1, 1):

multisample.count Sample positions
1 Sample 0: (0.5, 0.5)
4 Sample 0: (0.375, 0.125)
Sample 1: (0.875, 0.375)
Sample 2: (0.125, 0.625)
Sample 3: (0.625, 0.875)

Implementations must use the standard sample pattern for the given multisample.count when performing rasterization.

Let’s define a FragmentDestination to contain:

position

the 2D pixel position using framebuffer coordinates

sampleIndex

an integer in case § 23.2.10 Per-Sample Shading is active, or null otherwise

We’ll also use a notion of normalized device coordinates, or NDC. In this coordinate system, the viewport bounds range in X and Y from -1 to 1, and in Z from 0 to 1.

Rasterization produces a list of RasterizationPoints, each containing the following data:

destination

refers to FragmentDestination

coverageMask

refers to multisample coverage mask (see § 23.2.11 Sample Masking)

frontFacing

is true if it’s a point on the front face of a primitive

perspectiveDivisor

refers to interpolated 1.0 ÷ W across the primitive

depth

refers to the depth in viewport coordinates, i.e. between the [[viewport]] minDepth and maxDepth.

primitiveVertices

refers to the list of vertex outputs forming the primitive

barycentricCoordinates

refers to § 23.2.5.3 Barycentric coordinates

rasterize(primitiveList, state)

Arguments:

Returns: list of RasterizationPoint.

Each primitive in primitiveList is processed independently. However, the order of primitives affects later stages, such as depth/stencil operations and pixel writes.

  1. First, the clipped vertices are transformed into NDC - normalized device coordinates. Given the output position p, the NDC position and perspective divisor are:

    ndc(p) = vector(p.x ÷ p.w, p.y ÷ p.w, p.z ÷ p.w)

    divisor(p) = 1.0 ÷ p.w

  2. Let vp be state.[[viewport]]. Map the NDC position n into viewport coordinates:

    • Compute framebuffer coordinates from the render target offset and size:

      framebufferCoords(n) = vector(vp.x + 0.5 × (n.x + 1) × vp.width, vp.y + 0.5 × (−n.y + 1) × vp.height)

    • Compute depth by linearly mapping [0,1] to the viewport depth range:

      depth(n) = vp.minDepth + n.z × ( vp.maxDepth - vp.minDepth )

  3. Let rasterizationPoints be the list of points, each having its attributes (divisor(p), framebufferCoords(n), depth(n), etc.) interpolated according to its position on the primitive, using the same interpolation as § 23.2.4 Primitive Clipping. If the attribute is user-defined (not a built-in output value) then the interpolation type specified by the @interpolate WGSL attribute is used.

  4. Proceed with a specific rasterization algorithm, depending on primitive.topology:

    "point-list"

    The point, if not filtered by § 23.2.4 Primitive Clipping, goes into § 23.2.5.1 Point Rasterization.

    "line-list" or "line-strip"

    The line cut by § 23.2.4 Primitive Clipping goes into § 23.2.5.2 Line Rasterization.

    "triangle-list" or "triangle-strip"

    The polygon produced in § 23.2.4 Primitive Clipping goes into § 23.2.5.4 Polygon Rasterization.

  5. Remove all the points rp from rasterizationPoints that have rp.destination.position outside of state.[[scissorRect]].

  6. Return rasterizationPoints.

23.2.5.1. Point Rasterization

A single FragmentDestination is selected within the pixel containing the framebuffer coordinates of the point.

The coverage mask depends on multi-sampling mode:

sample-frequency

coverageMask = 1 ≪ sampleIndex

pixel-frequency multi-sampling

coverageMask = 1 ≪ descriptor.multisample.count − 1

no multi-sampling

coverageMask = 1

23.2.5.2. Line Rasterization

The exact algorithm used for line rasterization is not defined, and may differ between implementations. For example, the line may be drawn using § 23.2.5.4 Polygon Rasterization of a 1px-width rectangle around the line segment, or using Bresenham’s line algorithm to select the FragmentDestinations.

Note: See Basic Line Segment Rasterization and Bresenham Line Segment Rasterization in the Vulkan 1.3 spec for more details of how line these line rasterization algorithms may be implemented.

23.2.5.3. Barycentric coordinates

Barycentric coordinates is a list of n numbers bi, defined for a point p inside a convex polygon with n vertices vi in framebuffer space. Each bi is in range 0 to 1, inclusive, and represents the proximity to vertex vi. Their sum is always constant:

∑ (bi) = 1

These coordinates uniquely specify any point p within the polygon (or on its boundary) as:

p = ∑ (bi × pi)

For a polygon with 3 vertices - a triangle, barycentric coordinates of any point p can be computed as follows:

Apolygon = A(v1, v2, v3) b1 = A(p, b2, b3) ÷ Apolygon b2 = A(b1, p, b3) ÷ Apolygon b3 = A(b1, b2, p) ÷ Apolygon

Where A(list of points) is the area of the polygon with the given set of vertices.

For polygons with more than 3 vertices, the exact algorithm is implementation-dependent. One of the possible implementations is to triangulate the polygon and compute the barycentrics of a point based on the triangle it falls into.

23.2.5.4. Polygon Rasterization

A polygon is front-facing if it’s oriented towards the projection. Otherwise, the polygon is back-facing.

rasterize polygon()

Arguments:

Returns: list of RasterizationPoint.

  1. Let rasterizationPoints be an empty list.

  2. Let v(i) be the framebuffer coordinates for the clipped vertex number i (starting with 1) in a rasterized polygon of n vertices.

    Note: this section uses the term "polygon" instead of a "triangle", since § 23.2.4 Primitive Clipping stage may have introduced additional vertices. This is non-observable by the application.

  3. Determine if the polygon is front-facing, which depends on the sign of the area occupied by the polygon in framebuffer coordinates:

    area = 0.5 × ((v1.x × vn.y − vn.x × v1.y) + ∑ (vi+1.x × vi.y − vi.x × vi+1.y))

    The sign of area is interpreted based on the primitive.frontFace:

    "ccw"

    area > 0 is considered front-facing, otherwise back-facing

    "cw"

    area < 0 is considered front-facing, otherwise back-facing

  4. Cull based on primitive.cullMode:

    "none"

    All polygons pass this test.

    "front"

    The front-facing polygons are discarded, and do not process in later stages of the render pipeline.

    "back"

    The back-facing polygons are discarded.

  5. Determine a set of fragments inside the polygon in framebuffer space - these are locations scheduled for the per-fragment operations. This operation is known as "point sampling". The logic is based on descriptor.multisample:

    disabled

    Fragments are associated with pixel centers. That is, all the points with coordinates C, where fract(C) = vector2(0.5, 0.5) in the framebuffer space, enclosed into the polygon, are included. If a pixel center is on the edge of the polygon, whether or not it’s included is not defined.

    Note: this becomes a subject of precision for the rasterizer.

    enabled

    Each pixel is associated with descriptor.multisample.count locations, which are implementation-defined. The locations are ordered, and the list is the same for each pixel of the framebuffer. Each location corresponds to one fragment in the multisampled framebuffer.

    The rasterizer builds a mask of locations being hit inside each pixel and provides is as "sample-mask" built-in to the fragment shader.

  6. For each produced fragment of type FragmentDestination:

    1. Let rp be a new RasterizationPoint object

    2. Compute the list b as § 23.2.5.3 Barycentric coordinates of that fragment. Set rp.barycentricCoordinates to b.

    3. Let di be the depth value of vi.

    4. Set rp.depth to ∑ (bi × di)

    5. Append rp to rasterizationPoints.

  7. Return rasterizationPoints.

23.2.6. Fragment Processing

The fragment processing stage is a programmable stage of the render pipeline that computes the fragment data (often a color) to be written into render targets.

This stage produces a Fragment for each RasterizationPoint:

process fragment(rp, descriptor, state)

Arguments:

Returns: Fragment or null.

  1. Let fragmentDesc be descriptor.fragment.

  2. Let depthStencilDesc be descriptor.depthStencil.

  3. Let fragment be a new Fragment object.

  4. Set fragment.destination to rp.destination.

  5. Set fragment.frontFacing to rp.frontFacing.

  6. Set fragment.coverageMask to rp.coverageMask.

  7. Set fragment.depth to rp.depth.

  8. If frag_depth builtin is not produced by the shader:

    1. Set fragment.depthPassed to the result of compare fragment(fragment.destination, fragment.depth, "depth", state.[[depthStencilAttachment]], depthStencilDesc?.depthCompare).

  9. Set stencilState to depthStencilDesc?.stencilFront if rp.frontFacing is true and depthStencilDesc?.stencilBack otherwise.

  10. Set fragment.stencilPassed to the result of compare fragment(fragment.destination, state.[[stencilReference]], "stencil", state.[[depthStencilAttachment]], stencilState?.compare).

  11. If fragmentDesc is not null:

    1. If fragment.depthPassed is false, the frag_depth builtin is not produced by the shader entry point, and the shader entry point does not write to any storage bindings, the following steps may be skipped.

    2. Set the shader input builtins. For each non-composite argument of the entry point, annotated as a builtin, set its value based on the annotation:

      position

      vec4<f32>(rp.destination.position, rp.depth, rp.perspectiveDivisor)

      front_facing

      rp.frontFacing

      sample_index

      rp.destination.sampleIndex

      sample_mask

      rp.coverageMask

    3. For each user-specified shader stage input of the fragment stage:

      1. Let value be the interpolated fragment input, based on rp.barycentricCoordinates, rp.primitiveVertices, and the interpolation qualifier on the input.

      2. Set the corresponding fragment shader location input to value.

    4. Invoke the fragment shader entry point described by fragmentDesc.

      The device may become lost if shader execution does not end in a reasonable amount of time, as determined by the user agent.

    5. If the fragment issued discard, return null.

    6. Set fragment.colors to the user-specified shader stage output values from the shader.

    7. Take the shader output builtins:

      1. If frag_depth builtin is produced by the shader as value:

        1. Let vp be state.[[viewport]].

        2. Set fragment.depth to clamp(value, vp.minDepth, vp.maxDepth).

        3. Set fragment.depthPassed to the result of compare fragment(fragment.destination, fragment.depth, "depth", state.[[depthStencilAttachment]], depthStencilDesc?.depthCompare).

    8. If sample_mask builtin is produced by the shader as value:

      1. Set fragment.coverageMask to fragment.coverageMaskvalue.

    Otherwise we are in § 23.2.8 No Color Output mode, and fragment.colors is empty.

  12. Return fragment.

compare fragment(destination, value, aspect, attachment, compareFunc)

Arguments:

Returns: true if the comparison passes, or false otherwise

Processing of fragments happens in parallel, while any side effects, such as writes into GPUBufferBindingType "storage" bindings, may happen in any order.

23.2.7. Output Merging

Output merging is a fixed-function stage of the render pipeline that outputs the fragment color, depth and stencil data to be written into the render pass attachments.

process depth stencil(fragment, pipeline, state)

Arguments:

  1. Let depthStencilDesc be pipeline.[[descriptor]].depthStencil.

  2. If pipeline.[[writesDepth]] is true and fragment.depthPassed is true:

    1. Set the value of the depth aspect of state.[[depthStencilAttachment]] at fragment.destination to fragment.depth.

  3. If pipeline.[[writesStencil]] is true:

    1. Set stencilState to depthStencilDesc.stencilFront if fragment.frontFacing is true and depthStencilDesc.stencilBack otherwise.

    2. If fragment.stencilPassed is false:

      • Let stencilOp be stencilState.failOp.

      Else if fragment.depthPassed is false:

      Else:

      • Let stencilOp be stencilState.passOp.

    3. Update the value of the stencil aspect of state.[[depthStencilAttachment]] at fragment.destination by performing the operation described by stencilOp.

The depth input to this stage, if any, is clamped to the current [[viewport]] depth range (regardless of whether the fragment shader stage writes the frag_depth builtin).

process color attachments(fragment, pipeline, state)

Arguments:

  1. If fragment.depthPassed is false or fragment.stencilPassed is false, return.

  2. Let targets be pipeline.[[descriptor]].fragment.targets.

  3. For each attachment of state.[[colorAttachments]]:

    1. Let color be the value from fragment.colors that corresponds with attachment.

    2. Let targetDesc be the targets entry that corresponds with attachment.

    3. If targetDesc.blend is provided:

      1. Let colorBlend be targetDesc.blend.color.

      2. Let alphaBlend be targetDesc.blend.alpha.

      3. Set the RGB components of color to the value computed by performing the operation described by colorBlend.operation with the values described by colorBlend.srcFactor and colorBlend.dstFactor.

      4. Set the alpha component of color to the value computed by performing the operation described by alphaBlend.operation with the values described by alphaBlend.srcFactor and alphaBlend.dstFactor.

    4. Set the value of attachment at fragment.destination to color.

23.2.8. No Color Output

In no-color-output mode, pipeline does not produce any color attachment outputs.

The pipeline still performs rasterization and produces depth values based on the vertex position output. The depth testing and stencil operations can still be used.

23.2.9. Alpha to Coverage

In alpha-to-coverage mode, an additional alpha-to-coverage mask of MSAA samples is generated based on the alpha component of the fragment shader output value at @location(0).

The algorithm of producing the extra mask is platform-dependent and can vary for different pixels. It guarantees that:

23.2.10. Per-Sample Shading

When rendering into multisampled render attachments, fragment shaders can be run once per-pixel or once per-sample. Fragment shaders must run once per-sample if either the sample_index builtin or sample interpolation sampling is used and contributes to the shader output. Otherwise fragment shaders may run once per-pixel with the result broadcast out to each of the samples included in the final sample mask.

When using per-sample shading, the color output for sample N is produced by the fragment shader execution with sample_index == N for the current pixel.

23.2.11. Sample Masking

The final sample mask for a pixel is computed as: rasterization mask & mask & shader-output mask.

Only the lower count bits of the mask are considered.

If the least-significant bit at position N of the final sample mask has value of "0", the sample color outputs (corresponding to sample N) to all attachments of the fragment shader are discarded. Also, no depth test or stencil operations are executed on the relevant samples of the depth-stencil attachment.

The rasterization mask is produced by the rasterization stage, based on the shape of the rasterized polygon. The samples included in the shape get the relevant bits 1 in the mask.

The shader-output mask takes the output value of "sample_mask" builtin in the fragment shader. If the builtin is not output from the fragment shader, and alphaToCoverageEnabled is enabled, the shader-output mask becomes the alpha-to-coverage mask. Otherwise, it defaults to 0xFFFFFFFF.

24. Type Definitions

typedef [EnforceRange] unsigned long GPUBufferDynamicOffset;
typedef [EnforceRange] unsigned long GPUStencilValue;
typedef [EnforceRange] unsigned long GPUSampleMask;
typedef [EnforceRange] long GPUDepthBias;

typedef [EnforceRange] unsigned long long GPUSize64;
typedef [EnforceRange] unsigned long GPUIntegerCoordinate;
typedef [EnforceRange] unsigned long GPUIndex32;
typedef [EnforceRange] unsigned long GPUSize32;
typedef [EnforceRange] long GPUSignedOffset32;

typedef unsigned long long GPUSize64Out;
typedef unsigned long GPUIntegerCoordinateOut;
typedef unsigned long GPUSize32Out;

typedef unsigned long GPUFlagsConstant;

24.1. Colors & Vectors

dictionary GPUColorDict {
    required double r;
    required double g;
    required double b;
    required double a;
};
typedef (sequence<double> or GPUColorDict) GPUColor;

Note: double is large enough to precisely hold 32-bit signed/unsigned integers and single-precision floats.

r, of type double

The red channel value.

g, of type double

The green channel value.

b, of type double

The blue channel value.

a, of type double

The alpha channel value.

For a given GPUColor value color, depending on its type, the syntax:
validate GPUColor shape(color)

Arguments:

Returns: undefined

Content timeline steps:

  1. Throw a TypeError if color is a sequence and color.size ≠ 4.

dictionary GPUOrigin2DDict {
    GPUIntegerCoordinate x = 0;
    GPUIntegerCoordinate y = 0;
};
typedef (sequence<GPUIntegerCoordinate> or GPUOrigin2DDict) GPUOrigin2D;
For a given GPUOrigin2D value origin, depending on its type, the syntax:
validate GPUOrigin2D shape(origin)

Arguments:

Returns: undefined

Content timeline steps:

  1. Throw a TypeError if origin is a sequence and origin.size > 2.

dictionary GPUOrigin3DDict {
    GPUIntegerCoordinate x = 0;
    GPUIntegerCoordinate y = 0;
    GPUIntegerCoordinate z = 0;
};
typedef (sequence<GPUIntegerCoordinate> or GPUOrigin3DDict) GPUOrigin3D;
For a given GPUOrigin3D value origin, depending on its type, the syntax:
validate GPUOrigin3D shape(origin)

Arguments:

Returns: undefined

Content timeline steps:

  1. Throw a TypeError if origin is a sequence and origin.size > 3.

dictionary GPUExtent3DDict {
    required GPUIntegerCoordinate width;
    GPUIntegerCoordinate height = 1;
    GPUIntegerCoordinate depthOrArrayLayers = 1;
};
typedef (sequence<GPUIntegerCoordinate> or GPUExtent3DDict) GPUExtent3D;
width, of type GPUIntegerCoordinate

The width of the extent.

height, of type GPUIntegerCoordinate, defaulting to 1

The height of the extent.

depthOrArrayLayers, of type GPUIntegerCoordinate, defaulting to 1

The depth of the extent or the number of array layers it contains. If used with a GPUTexture with a GPUTextureDimension of "3d" defines the depth of the texture. If used with a GPUTexture with a GPUTextureDimension of "2d" defines the number of array layers in the texture.

For a given GPUExtent3D value extent, depending on its type, the syntax:
validate GPUExtent3D shape(extent)

Arguments:

Returns: undefined

Content timeline steps:

  1. Throw a TypeError if:

25. Feature Index

25.1. "core-features-and-limits"

Allows all Core WebGPU features and limits to be used.

Note: This is currently available on all adapters and enabled automatically on all devices even if not requested.

25.2. "depth-clip-control"

Allows depth clipping to be disabled.

This feature adds the following optional API surfaces:

25.3. "depth32float-stencil8"

Allows for explicit creation of textures of format "depth32float-stencil8".

This feature adds the following optional API surfaces:

25.4. "texture-compression-bc"

Allows for explicit creation of textures of BC compressed formats which include the "S3TC", "RGTC", and "BPTC" formats. Only supports 2D textures.

Note: Adapters which support "texture-compression-bc" do not always support "texture-compression-bc-sliced-3d". To use "texture-compression-bc-sliced-3d", "texture-compression-bc" must be enabled explicitly as this feature does not enable the BC formats.

This feature adds the following optional API surfaces:

25.5. "texture-compression-bc-sliced-3d"

Allows the 3d dimension for textures with BC compressed formats.

Note: Adapters which support "texture-compression-bc" do not always support "texture-compression-bc-sliced-3d". To use "texture-compression-bc-sliced-3d", "texture-compression-bc" must be enabled explicitly as this feature does not enable the BC formats.

This feature adds no optional API surfaces.

25.6. "texture-compression-etc2"

Allows for explicit creation of textures of ETC2 compressed formats. Only supports 2D textures.

This feature adds the following optional API surfaces:

25.7. "texture-compression-astc"

Allows for explicit creation of textures of ASTC compressed formats. Only supports 2D textures.

This feature adds the following optional API surfaces:

25.8. "texture-compression-astc-sliced-3d"

Allows the 3d dimension for textures with ASTC compressed formats.

Note: Adapters which support "texture-compression-astc" do not always support "texture-compression-astc-sliced-3d". To use "texture-compression-astc-sliced-3d", "texture-compression-astc" must be enabled explicitly as this feature does not enable the ASTC formats.

This feature adds no optional API surfaces.

25.9. "timestamp-query"

Adds the ability to query timestamps from GPU command buffers. See § 20.4 Timestamp Query.

This feature adds the following optional API surfaces:

25.10. "indirect-first-instance"

Allows the use of non-zero firstInstance values in indirect draw parameters and indirect drawIndexed parameters.

This feature adds no optional API surfaces.

25.11. "shader-f16"

Allows the use of the half-precision floating-point type f16 in WGSL.

This feature adds the following optional API surfaces:

25.12. "rg11b10ufloat-renderable"

Allows the RENDER_ATTACHMENT usage on textures with format "rg11b10ufloat", and also allows textures of that format to be blended, multisampled, and resolved.

This feature adds no optional API surfaces.

Enabling "texture-formats-tier1" at device creation will also enable "rg11b10ufloat-renderable".

25.13. "bgra8unorm-storage"

Allows the STORAGE_BINDING usage on textures with format "bgra8unorm".

This feature adds no optional API surfaces.

25.14. "float32-filterable"

Makes textures with formats "r32float", "rg32float", and "rgba32float" filterable.

25.15. "float32-blendable"

Makes textures with formats "r32float", "rg32float", and "rgba32float" blendable.

25.16. "clip-distances"

Allows the use of clip_distances in WGSL.

This feature adds the following optional API surfaces:

25.17. "dual-source-blending"

Allows the use of blend_src in WGSL and simultaneously using both pixel shader outputs (@blend_src(0) and @blend_src(1)) as inputs to a blending operation with the single color attachment at location 0.

This feature adds the following optional API surfaces:

25.18. "subgroups"

Allows the use of the subgroup and quad operations in WGSL.

This feature adds no optional API surfaces, but the following entries of GPUAdapterInfo expose real values whenever the feature is available on the adapter:

25.19. "texture-formats-tier1"

Supports the below new GPUTextureFormats with the RENDER_ATTACHMENT, blendable, multisampling capabilities and the STORAGE_BINDING capability with the "read-only" and "write-only" GPUStorageTextureAccesses:

Allows the RENDER_ATTACHMENT, blendable, multisampling and resolve capabilities on below GPUTextureFormats:

Allows the "read-only" or "write-only" GPUStorageTextureAccess on below GPUTextureFormats:

Enabling "texture-formats-tier2" at device creation will also enable "texture-formats-tier1".

Enabling "texture-formats-tier1" at device creation will also enable "rg11b10ufloat-renderable".

25.20. "texture-formats-tier2"

Allows the "read-write" GPUStorageTextureAccess on below GPUTextureFormats:

Enabling "texture-formats-tier2" at device creation will also enable "texture-formats-tier1".

26. Appendices

26.1. Texture Format Capabilities

26.1.1. Plain color formats

All supported plain color formats support usages COPY_SRC, COPY_DST, and TEXTURE_BINDING, and dimension "3d".

The RENDER_ATTACHMENT and STORAGE_BINDING columns specify support for GPUTextureUsage.RENDER_ATTACHMENT and GPUTextureUsage.STORAGE_BINDING usage respectively.

The render target pixel byte cost and render target component alignment are used to validate the maxColorAttachmentBytesPerSample limit.

Note: The texel block memory cost of each of these formats is the same as its texel block copy footprint.

Format Required Feature GPUTextureSampleType RENDER_ATTACHMENT blendable multisampling resolve STORAGE_BINDING Texel block copy footprint (Bytes) Render target pixel byte cost (Bytes)
"write-only" "read-only" "read-write"
8 bits per component (1-byte render target component alignment)
r8unorm "float",
"unfilterable-float"
If "texture-formats-tier1" is enabled If "texture-formats-tier2" is enabled 1
r8snorm "float",
"unfilterable-float"
If "texture-formats-tier1" is enabled 1
r8uint "uint" If "texture-formats-tier1" is enabled If "texture-formats-tier2" is enabled 1
r8sint "sint" If "texture-formats-tier1" is enabled If "texture-formats-tier2" is enabled 1
rg8unorm "float",
"unfilterable-float"
If "texture-formats-tier1" is enabled 2
rg8snorm "float",
"unfilterable-float"
If "texture-formats-tier1" is enabled 2
rg8uint "uint" If "texture-formats-tier1" is enabled 2
rg8sint "sint" If "texture-formats-tier1" is enabled 2
rgba8unorm "float",
"unfilterable-float"
If "texture-formats-tier2" is enabled 4 8
rgba8unorm-srgb "float",
"unfilterable-float"
4 8
rgba8snorm "float",
"unfilterable-float"
If "texture-formats-tier1" is enabled 4
rgba8uint "uint" If "texture-formats-tier2" is enabled 4
rgba8sint "sint" If "texture-formats-tier2" is enabled 4
bgra8unorm "float",
"unfilterable-float"
If "bgra8unorm-storage" is enabled 4 8
bgra8unorm-srgb "float",
"unfilterable-float"
4 8
16 bits per component (2-byte render target component alignment)
r16unorm "texture-formats-tier1" "unfilterable-float" 2
r16snorm "texture-formats-tier1" "unfilterable-float" 2
r16uint "uint" If "texture-formats-tier1" is enabled If "texture-formats-tier2" is enabled 2
r16sint "sint" If "texture-formats-tier1" is enabled If "texture-formats-tier2" is enabled 2
r16float "float",
"unfilterable-float"
If "texture-formats-tier1" is enabled If "texture-formats-tier2" is enabled 2
rg16unorm "texture-formats-tier1" "unfilterable-float" 4
rg16snorm "texture-formats-tier1" "unfilterable-float" 4
rg16uint "uint" If "texture-formats-tier1" is enabled 4
rg16sint "sint" If "texture-formats-tier1" is enabled 4
rg16float "float",
"unfilterable-float"
If "texture-formats-tier1" is enabled 4
rgba16unorm "texture-formats-tier1" "unfilterable-float" 8
rgba16snorm "texture-formats-tier1" "unfilterable-float" 8
rgba16uint "uint" If "texture-formats-tier2" is enabled 8
rgba16sint "sint" If "texture-formats-tier2" is enabled 8
rgba16float "float",
"unfilterable-float"
If "texture-formats-tier2" is enabled 8
32 bits per component (4-byte render target component alignment)
r32uint "uint" 4
r32sint "sint" 4
r32float "unfilterable-float" If "float32-blendable" is enabled 4
rg32uint "uint" 8
rg32sint "sint" 8
rg32float "unfilterable-float" If "float32-blendable" is enabled 8
rgba32uint "uint" If "texture-formats-tier2" is enabled 16
rgba32sint "sint" If "texture-formats-tier2" is enabled 16
rgba32float "unfilterable-float" If "float32-blendable" is enabled If "texture-formats-tier2" is enabled 16
mixed component width, 32 bits per texel (4-byte render target component alignment)
rgb10a2uint "uint" If "texture-formats-tier1" is enabled 4 8
rgb10a2unorm "float",
"unfilterable-float"
If "texture-formats-tier1" is enabled 4 8
rg11b10ufloat "float",
"unfilterable-float"
If "rg11b10ufloat-renderable" is enabled If "texture-formats-tier1" is enabled 4 8

26.1.2. Depth-stencil formats

A depth-or-stencil format is any format with depth and/or stencil aspects. A combined depth-stencil format is a depth-or-stencil format that has both depth and stencil aspects.

All depth-or-stencil formats support the COPY_SRC, COPY_DST, TEXTURE_BINDING, and RENDER_ATTACHMENT usages. All of these formats support multisampling. However, certain copy operations also restrict the source and destination formats, and none of these formats support textures with "3d" dimension.

Depth textures cannot be used with "filtering" samplers, but can always be used with "comparison" samplers even if they use filtering.

Format
NOTE:
Texel block memory cost (Bytes)
Aspect GPUTextureSampleType Valid texel copy source Valid texel copy destination Texel block copy footprint (Bytes) Aspect-specific format
stencil8 1 − 4 stencil "uint" 1 stencil8
depth16unorm 2 depth "depth", "unfilterable-float" 2 depth16unorm
depth24plus 4 depth "depth", "unfilterable-float" depth24plus
depth24plus-stencil8 4 − 8 depth "depth", "unfilterable-float" depth24plus
stencil "uint" 1 stencil8
depth32float 4 depth "depth", "unfilterable-float" 4 depth32float
depth32float-stencil8 5 − 8 depth "depth", "unfilterable-float" 4 depth32float
stencil "uint" 1 stencil8

24-bit depth refers to a 24-bit unsigned normalized depth format with a range from 0.0 to 1.0, which would be spelled "depth24unorm" if exposed.

26.1.2.1. Reading and Sampling Depth/Stencil Textures

It is possible to bind a depth-aspect GPUTextureView to either a texture_depth_* binding or a binding with other non-depth 2d/cube texture types.

A stencil-aspect GPUTextureView must be bound to a normal texture binding type. The sampleType in the GPUBindGroupLayout must be "uint".

Reading or sampling the depth or stencil aspect of a texture behaves as if the texture contains the values (V, X, X, X), where V is the actual depth or stencil value, and each X is an implementation-defined unspecified value.

For depth-aspect bindings, the unspecified values are not visible through bindings with texture_depth_* types.

If a depth texture is bound to tex with type texture_2d<f32>:

Note: Short of adding a new more constrained stencil sampler type (like depth), it’s infeasible for implementations to efficiently paper over the driver differences for depth/stencil reads. As this was not a portability pain point for WebGL, it’s not expected to be problematic in WebGPU. In practice, expect either (V, V, V, V) or (V, 0, 0, 1) (where V is the depth or stencil value), depending on hardware.

26.1.2.2. Copying Depth/Stencil Textures

The depth aspects of depth32float formats ("depth32float" and "depth32float-stencil8" have a limited range. As a result, copies into such textures are only valid from other textures of the same format.

The depth aspects of depth24plus formats ("depth24plus" and "depth24plus-stencil8") have opaque representations (implemented as either 24-bit depth or "depth32float"). As a result, depth-aspect texel copies are not allowed with these formats.

NOTE:
It is possible to imitate these disallowed copies:

26.1.3. Packed formats

All packed texture formats support COPY_SRC, COPY_DST, and TEXTURE_BINDING usages. All of these formats are filterable. None of these formats are renderable or support multisampling.

A compressed format is any format with a block size greater than 1×1.

Note: The texel block memory cost of each of these formats is the same as its texel block copy footprint.

Format Texel block copy footprint (Bytes) GPUTextureSampleType Texel block width/height "3d" Feature
rgb9e5ufloat 4 "float",
"unfilterable-float"
1 × 1
bc1-rgba-unorm 8 "float",
"unfilterable-float"
4 × 4 If "texture-compression-bc-sliced-3d" is enabled texture-compression-bc
bc1-rgba-unorm-srgb
bc2-rgba-unorm 16
bc2-rgba-unorm-srgb
bc3-rgba-unorm 16
bc3-rgba-unorm-srgb
bc4-r-unorm 8
bc4-r-snorm
bc5-rg-unorm 16
bc5-rg-snorm
bc6h-rgb-ufloat 16
bc6h-rgb-float
bc7-rgba-unorm 16
bc7-rgba-unorm-srgb
etc2-rgb8unorm 8 "float",
"unfilterable-float"
4 × 4 texture-compression-etc2
etc2-rgb8unorm-srgb
etc2-rgb8a1unorm 8
etc2-rgb8a1unorm-srgb
etc2-rgba8unorm 16
etc2-rgba8unorm-srgb
eac-r11unorm 8
eac-r11snorm
eac-rg11unorm 16
eac-rg11snorm
astc-4x4-unorm 16 "float",
"unfilterable-float"
4 × 4 If "texture-compression-astc-sliced-3d" is enabled texture-compression-astc
astc-4x4-unorm-srgb
astc-5x4-unorm 16 5 × 4
astc-5x4-unorm-srgb
astc-5x5-unorm 16 5 × 5
astc-5x5-unorm-srgb
astc-6x5-unorm 16 6 × 5
astc-6x5-unorm-srgb
astc-6x6-unorm 16 6 × 6
astc-6x6-unorm-srgb
astc-8x5-unorm 16 8 × 5
astc-8x5-unorm-srgb
astc-8x6-unorm 16 8 × 6
astc-8x6-unorm-srgb
astc-8x8-unorm 16 8 × 8
astc-8x8-unorm-srgb
astc-10x5-unorm 16 10 × 5
astc-10x5-unorm-srgb
astc-10x6-unorm 16 10 × 6
astc-10x6-unorm-srgb
astc-10x8-unorm 16 10 × 8
astc-10x8-unorm-srgb
astc-10x10-unorm 16 10 × 10
astc-10x10-unorm-srgb
astc-12x10-unorm 16 12 × 10
astc-12x10-unorm-srgb
astc-12x12-unorm 16 12 × 12
astc-12x12-unorm-srgb

Conformance

Document conventions

Conformance requirements are expressed with a combination of descriptive assertions and RFC 2119 terminology. The key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in the normative parts of this document are to be interpreted as described in RFC 2119. However, for readability, these words do not appear in all uppercase letters in this specification.

All of the text of this specification is normative except sections explicitly marked as non-normative, examples, and notes. [RFC2119]

Examples in this specification are introduced with the words “for example” or are set apart from the normative text with class="example", like this:

This is an example of an informative example.

Informative notes begin with the word “Note” and are set apart from the normative text with class="note", like this:

Note, this is an informative note.

Conformant Algorithms

Requirements phrased in the imperative as part of algorithms (such as "strip any leading space characters" or "return false and abort these steps") are to be interpreted with the meaning of the key word ("must", "should", "may", etc) used in introducing the algorithm.

Conformance requirements phrased as algorithms or specific steps can be implemented in any manner, so long as the end result is equivalent. In particular, the algorithms defined in this specification are intended to be easy to understand and are not intended to be performant. Implementers are encouraged to optimize.

Index

Terms defined by this specification

Terms defined by reference

References

Normative References

[DOM]
Anne van Kesteren. DOM Standard. Living Standard. URL: https://dom.spec.whatwg.org/
[ECMASCRIPT]
ECMAScript Language Specification. URL: https://tc39.es/ecma262/multipage/
[HR-TIME-3]
Yoav Weiss. High Resolution Time. 7 November 2024. WD. URL: https://www.w3.org/TR/hr-time-3/
[HTML]
Anne van Kesteren; et al. HTML Standard. Living Standard. URL: https://html.spec.whatwg.org/multipage/
[I18N-GLOSSARY]
Richard Ishida; Addison Phillips. Internationalization Glossary. 17 October 2024. NOTE. URL: https://www.w3.org/TR/i18n-glossary/
[INFRA]
Anne van Kesteren; Domenic Denicola. Infra Standard. Living Standard. URL: https://infra.spec.whatwg.org/
[RFC2119]
S. Bradner. Key words for use in RFCs to Indicate Requirement Levels. March 1997. Best Current Practice. URL: https://datatracker.ietf.org/doc/html/rfc2119
[WEBCODECS]
Paul Adenot; Eugene Zemtsov. WebCodecs. 14 May 2025. WD. URL: https://www.w3.org/TR/webcodecs/
[WEBGL-1]
Dean Jackson; Jeff Gilbert. WebGL Specification, Version 1.0. 9 August 2017. URL: https://www.khronos.org/registry/webgl/specs/latest/1.0/
[WEBIDL]
Edgar Chen; Timothy Gu. Web IDL Standard. Living Standard. URL: https://webidl.spec.whatwg.org/
[WEBXR]
Brandon Jones; Manish Goregaokar; Rik Cabanier. WebXR Device API. 17 April 2025. CRD. URL: https://www.w3.org/TR/webxr/
[WGSL]
Alan Baker; Mehmet Oguz Derin; David Neto. WebGPU Shading Language. 3 July 2025. CRD. URL: https://www.w3.org/TR/WGSL/

Informative References

[MEDIAQUERIES-5]
Dean Jackson; et al. Media Queries Level 5. 18 December 2021. WD. URL: https://www.w3.org/TR/mediaqueries-5/
[SERVICE-WORKERS]
Yoshisato Yanagisawa; Monica CHINTALA. Service Workers. 6 March 2025. CRD. URL: https://www.w3.org/TR/service-workers/
[VULKAN]
The Khronos Vulkan Working Group. Vulkan 1.3. URL: https://registry.khronos.org/vulkan/specs/1.3/html/vkspec.html

IDL Index

interface mixin GPUObjectBase {
    attribute USVString label;
};

dictionary GPUObjectDescriptorBase {
    USVString label = "";
};

[Exposed=(Window, Worker), SecureContext]
interface GPUSupportedLimits {
    readonly attribute unsigned long maxTextureDimension1D;
    readonly attribute unsigned long maxTextureDimension2D;
    readonly attribute unsigned long maxTextureDimension3D;
    readonly attribute unsigned long maxTextureArrayLayers;
    readonly attribute unsigned long maxBindGroups;
    readonly attribute unsigned long maxBindGroupsPlusVertexBuffers;
    readonly attribute unsigned long maxBindingsPerBindGroup;
    readonly attribute unsigned long maxDynamicUniformBuffersPerPipelineLayout;
    readonly attribute unsigned long maxDynamicStorageBuffersPerPipelineLayout;
    readonly attribute unsigned long maxSampledTexturesPerShaderStage;
    readonly attribute unsigned long maxSamplersPerShaderStage;
    readonly attribute unsigned long maxStorageBuffersPerShaderStage;
    readonly attribute unsigned long maxStorageTexturesPerShaderStage;
    readonly attribute unsigned long maxUniformBuffersPerShaderStage;
    readonly attribute unsigned long long maxUniformBufferBindingSize;
    readonly attribute unsigned long long maxStorageBufferBindingSize;
    readonly attribute unsigned long minUniformBufferOffsetAlignment;
    readonly attribute unsigned long minStorageBufferOffsetAlignment;
    readonly attribute unsigned long maxVertexBuffers;
    readonly attribute unsigned long long maxBufferSize;
    readonly attribute unsigned long maxVertexAttributes;
    readonly attribute unsigned long maxVertexBufferArrayStride;
    readonly attribute unsigned long maxInterStageShaderVariables;
    readonly attribute unsigned long maxColorAttachments;
    readonly attribute unsigned long maxColorAttachmentBytesPerSample;
    readonly attribute unsigned long maxComputeWorkgroupStorageSize;
    readonly attribute unsigned long maxComputeInvocationsPerWorkgroup;
    readonly attribute unsigned long maxComputeWorkgroupSizeX;
    readonly attribute unsigned long maxComputeWorkgroupSizeY;
    readonly attribute unsigned long maxComputeWorkgroupSizeZ;
    readonly attribute unsigned long maxComputeWorkgroupsPerDimension;
};

[Exposed=(Window, Worker), SecureContext]
interface GPUSupportedFeatures {
    readonly setlike<DOMString>;
};

[Exposed=(Window, Worker), SecureContext]
interface WGSLLanguageFeatures {
    readonly setlike<DOMString>;
};

[Exposed=(Window, Worker), SecureContext]
interface GPUAdapterInfo {
    readonly attribute DOMString vendor;
    readonly attribute DOMString architecture;
    readonly attribute DOMString device;
    readonly attribute DOMString description;
    readonly attribute unsigned long subgroupMinSize;
    readonly attribute unsigned long subgroupMaxSize;
    readonly attribute boolean isFallbackAdapter;
};

interface mixin NavigatorGPU {
    [SameObject, SecureContext] readonly attribute GPU gpu;
};
Navigator includes NavigatorGPU;
WorkerNavigator includes NavigatorGPU;

[Exposed=(Window, Worker), SecureContext]
interface GPU {
    Promise<GPUAdapter?> requestAdapter(optional GPURequestAdapterOptions options = {});
    GPUTextureFormat getPreferredCanvasFormat();
    [SameObject] readonly attribute WGSLLanguageFeatures wgslLanguageFeatures;
};

dictionary GPURequestAdapterOptions {
    DOMString featureLevel = "core";
    GPUPowerPreference powerPreference;
    boolean forceFallbackAdapter = false;
    boolean xrCompatible = false;
};

enum GPUPowerPreference {
    "low-power",
    "high-performance",
};

[Exposed=(Window, Worker), SecureContext]
interface GPUAdapter {
    [SameObject] readonly attribute GPUSupportedFeatures features;
    [SameObject] readonly attribute GPUSupportedLimits limits;
    [SameObject] readonly attribute GPUAdapterInfo info;

    Promise<GPUDevice> requestDevice(optional GPUDeviceDescriptor descriptor = {});
};

dictionary GPUDeviceDescriptor
         : GPUObjectDescriptorBase {
    sequence<GPUFeatureName> requiredFeatures = [];
    record<DOMString, (GPUSize64 or undefined)> requiredLimits = {};
    GPUQueueDescriptor defaultQueue = {};
};

enum GPUFeatureName {
    "core-features-and-limits",
    "depth-clip-control",
    "depth32float-stencil8",
    "texture-compression-bc",
    "texture-compression-bc-sliced-3d",
    "texture-compression-etc2",
    "texture-compression-astc",
    "texture-compression-astc-sliced-3d",
    "timestamp-query",
    "indirect-first-instance",
    "shader-f16",
    "rg11b10ufloat-renderable",
    "bgra8unorm-storage",
    "float32-filterable",
    "float32-blendable",
    "clip-distances",
    "dual-source-blending",
    "subgroups",
    "texture-formats-tier1",
    "texture-formats-tier2",
};

[Exposed=(Window, Worker), SecureContext]
interface GPUDevice : EventTarget {
    [SameObject] readonly attribute GPUSupportedFeatures features;
    [SameObject] readonly attribute GPUSupportedLimits limits;
    [SameObject] readonly attribute GPUAdapterInfo adapterInfo;

    [SameObject] readonly attribute GPUQueue queue;

    undefined destroy();

    GPUBuffer createBuffer(GPUBufferDescriptor descriptor);
    GPUTexture createTexture(GPUTextureDescriptor descriptor);
    GPUSampler createSampler(optional GPUSamplerDescriptor descriptor = {});
    GPUExternalTexture importExternalTexture(GPUExternalTextureDescriptor descriptor);

    GPUBindGroupLayout createBindGroupLayout(GPUBindGroupLayoutDescriptor descriptor);
    GPUPipelineLayout createPipelineLayout(GPUPipelineLayoutDescriptor descriptor);
    GPUBindGroup createBindGroup(GPUBindGroupDescriptor descriptor);

    GPUShaderModule createShaderModule(GPUShaderModuleDescriptor descriptor);
    GPUComputePipeline createComputePipeline(GPUComputePipelineDescriptor descriptor);
    GPURenderPipeline createRenderPipeline(GPURenderPipelineDescriptor descriptor);
    Promise<GPUComputePipeline> createComputePipelineAsync(GPUComputePipelineDescriptor descriptor);
    Promise<GPURenderPipeline> createRenderPipelineAsync(GPURenderPipelineDescriptor descriptor);

    GPUCommandEncoder createCommandEncoder(optional GPUCommandEncoderDescriptor descriptor = {});
    GPURenderBundleEncoder createRenderBundleEncoder(GPURenderBundleEncoderDescriptor descriptor);

    GPUQuerySet createQuerySet(GPUQuerySetDescriptor descriptor);
};
GPUDevice includes GPUObjectBase;

[Exposed=(Window, Worker), SecureContext]
interface GPUBuffer {
    readonly attribute GPUSize64Out size;
    readonly attribute GPUFlagsConstant usage;

    readonly attribute GPUBufferMapState mapState;

    Promise<undefined> mapAsync(GPUMapModeFlags mode, optional GPUSize64 offset = 0, optional GPUSize64 size);
    ArrayBuffer getMappedRange(optional GPUSize64 offset = 0, optional GPUSize64 size);
    undefined unmap();

    undefined destroy();
};
GPUBuffer includes GPUObjectBase;

enum GPUBufferMapState {
    "unmapped",
    "pending",
    "mapped",
};

dictionary GPUBufferDescriptor
         : GPUObjectDescriptorBase {
    required GPUSize64 size;
    required GPUBufferUsageFlags usage;
    boolean mappedAtCreation = false;
};

typedef [EnforceRange] unsigned long GPUBufferUsageFlags;
[Exposed=(Window, Worker), SecureContext]
namespace GPUBufferUsage {
    const GPUFlagsConstant MAP_READ      = 0x0001;
    const GPUFlagsConstant MAP_WRITE     = 0x0002;
    const GPUFlagsConstant COPY_SRC      = 0x0004;
    const GPUFlagsConstant COPY_DST      = 0x0008;
    const GPUFlagsConstant INDEX         = 0x0010;
    const GPUFlagsConstant VERTEX        = 0x0020;
    const GPUFlagsConstant UNIFORM       = 0x0040;
    const GPUFlagsConstant STORAGE       = 0x0080;
    const GPUFlagsConstant INDIRECT      = 0x0100;
    const GPUFlagsConstant QUERY_RESOLVE = 0x0200;
};

typedef [EnforceRange] unsigned long GPUMapModeFlags;
[Exposed=(Window, Worker), SecureContext]
namespace GPUMapMode {
    const GPUFlagsConstant READ  = 0x0001;
    const GPUFlagsConstant WRITE = 0x0002;
};

[Exposed=(Window, Worker), SecureContext]
interface GPUTexture {
    GPUTextureView createView(optional GPUTextureViewDescriptor descriptor = {});

    undefined destroy();

    readonly attribute GPUIntegerCoordinateOut width;
    readonly attribute GPUIntegerCoordinateOut height;
    readonly attribute GPUIntegerCoordinateOut depthOrArrayLayers;
    readonly attribute GPUIntegerCoordinateOut mipLevelCount;
    readonly attribute GPUSize32Out sampleCount;
    readonly attribute GPUTextureDimension dimension;
    readonly attribute GPUTextureFormat format;
    readonly attribute GPUFlagsConstant usage;
};
GPUTexture includes GPUObjectBase;

dictionary GPUTextureDescriptor
         : GPUObjectDescriptorBase {
    required GPUExtent3D size;
    GPUIntegerCoordinate mipLevelCount = 1;
    GPUSize32 sampleCount = 1;
    GPUTextureDimension dimension = "2d";
    required GPUTextureFormat format;
    required GPUTextureUsageFlags usage;
    sequence<GPUTextureFormat> viewFormats = [];
};

enum GPUTextureDimension {
    "1d",
    "2d",
    "3d",
};

typedef [EnforceRange] unsigned long GPUTextureUsageFlags;
[Exposed=(Window, Worker), SecureContext]
namespace GPUTextureUsage {
    const GPUFlagsConstant COPY_SRC          = 0x01;
    const GPUFlagsConstant COPY_DST          = 0x02;
    const GPUFlagsConstant TEXTURE_BINDING   = 0x04;
    const GPUFlagsConstant STORAGE_BINDING   = 0x08;
    const GPUFlagsConstant RENDER_ATTACHMENT = 0x10;
};

[Exposed=(Window, Worker), SecureContext]
interface GPUTextureView {
};
GPUTextureView includes GPUObjectBase;

dictionary GPUTextureViewDescriptor
         : GPUObjectDescriptorBase {
    GPUTextureFormat format;
    GPUTextureViewDimension dimension;
    GPUTextureUsageFlags usage = 0;
    GPUTextureAspect aspect = "all";
    GPUIntegerCoordinate baseMipLevel = 0;
    GPUIntegerCoordinate mipLevelCount;
    GPUIntegerCoordinate baseArrayLayer = 0;
    GPUIntegerCoordinate arrayLayerCount;
};

enum GPUTextureViewDimension {
    "1d",
    "2d",
    "2d-array",
    "cube",
    "cube-array",
    "3d",
};

enum GPUTextureAspect {
    "all",
    "stencil-only",
    "depth-only",
};

enum GPUTextureFormat {
    // 8-bit formats
    "r8unorm",
    "r8snorm",
    "r8uint",
    "r8sint",

    // 16-bit formats
    "r16unorm",
    "r16snorm",
    "r16uint",
    "r16sint",
    "r16float",
    "rg8unorm",
    "rg8snorm",
    "rg8uint",
    "rg8sint",

    // 32-bit formats
    "r32uint",
    "r32sint",
    "r32float",
    "rg16unorm",
    "rg16snorm",
    "rg16uint",
    "rg16sint",
    "rg16float",
    "rgba8unorm",
    "rgba8unorm-srgb",
    "rgba8snorm",
    "rgba8uint",
    "rgba8sint",
    "bgra8unorm",
    "bgra8unorm-srgb",
    // Packed 32-bit formats
    "rgb9e5ufloat",
    "rgb10a2uint",
    "rgb10a2unorm",
    "rg11b10ufloat",

    // 64-bit formats
    "rg32uint",
    "rg32sint",
    "rg32float",
    "rgba16unorm",
    "rgba16snorm",
    "rgba16uint",
    "rgba16sint",
    "rgba16float",

    // 128-bit formats
    "rgba32uint",
    "rgba32sint",
    "rgba32float",

    // Depth/stencil formats
    "stencil8",
    "depth16unorm",
    "depth24plus",
    "depth24plus-stencil8",
    "depth32float",

    // "depth32float-stencil8" feature
    "depth32float-stencil8",

    // BC compressed formats usable if "texture-compression-bc" is both
    // supported by the device/user agent and enabled in requestDevice.
    "bc1-rgba-unorm",
    "bc1-rgba-unorm-srgb",
    "bc2-rgba-unorm",
    "bc2-rgba-unorm-srgb",
    "bc3-rgba-unorm",
    "bc3-rgba-unorm-srgb",
    "bc4-r-unorm",
    "bc4-r-snorm",
    "bc5-rg-unorm",
    "bc5-rg-snorm",
    "bc6h-rgb-ufloat",
    "bc6h-rgb-float",
    "bc7-rgba-unorm",
    "bc7-rgba-unorm-srgb",

    // ETC2 compressed formats usable if "texture-compression-etc2" is both
    // supported by the device/user agent and enabled in requestDevice.
    "etc2-rgb8unorm",
    "etc2-rgb8unorm-srgb",
    "etc2-rgb8a1unorm",
    "etc2-rgb8a1unorm-srgb",
    "etc2-rgba8unorm",
    "etc2-rgba8unorm-srgb",
    "eac-r11unorm",
    "eac-r11snorm",
    "eac-rg11unorm",
    "eac-rg11snorm",

    // ASTC compressed formats usable if "texture-compression-astc" is both
    // supported by the device/user agent and enabled in requestDevice.
    "astc-4x4-unorm",
    "astc-4x4-unorm-srgb",
    "astc-5x4-unorm",
    "astc-5x4-unorm-srgb",
    "astc-5x5-unorm",
    "astc-5x5-unorm-srgb",
    "astc-6x5-unorm",
    "astc-6x5-unorm-srgb",
    "astc-6x6-unorm",
    "astc-6x6-unorm-srgb",
    "astc-8x5-unorm",
    "astc-8x5-unorm-srgb",
    "astc-8x6-unorm",
    "astc-8x6-unorm-srgb",
    "astc-8x8-unorm",
    "astc-8x8-unorm-srgb",
    "astc-10x5-unorm",
    "astc-10x5-unorm-srgb",
    "astc-10x6-unorm",
    "astc-10x6-unorm-srgb",
    "astc-10x8-unorm",
    "astc-10x8-unorm-srgb",
    "astc-10x10-unorm",
    "astc-10x10-unorm-srgb",
    "astc-12x10-unorm",
    "astc-12x10-unorm-srgb",
    "astc-12x12-unorm",
    "astc-12x12-unorm-srgb",
};

[Exposed=(Window, Worker), SecureContext]
interface GPUExternalTexture {
};
GPUExternalTexture includes GPUObjectBase;

dictionary GPUExternalTextureDescriptor
         : GPUObjectDescriptorBase {
    required (HTMLVideoElement or VideoFrame) source;
    PredefinedColorSpace colorSpace = "srgb";
};

[Exposed=(Window, Worker), SecureContext]
interface GPUSampler {
};
GPUSampler includes GPUObjectBase;

dictionary GPUSamplerDescriptor
         : GPUObjectDescriptorBase {
    GPUAddressMode addressModeU = "clamp-to-edge";
    GPUAddressMode addressModeV = "clamp-to-edge";
    GPUAddressMode addressModeW = "clamp-to-edge";
    GPUFilterMode magFilter = "nearest";
    GPUFilterMode minFilter = "nearest";
    GPUMipmapFilterMode mipmapFilter = "nearest";
    float lodMinClamp = 0;
    float lodMaxClamp = 32;
    GPUCompareFunction compare;
    [Clamp] unsigned short maxAnisotropy = 1;
};

enum GPUAddressMode {
    "clamp-to-edge",
    "repeat",
    "mirror-repeat",
};

enum GPUFilterMode {
    "nearest",
    "linear",
};

enum GPUMipmapFilterMode {
    "nearest",
    "linear",
};

enum GPUCompareFunction {
    "never",
    "less",
    "equal",
    "less-equal",
    "greater",
    "not-equal",
    "greater-equal",
    "always",
};

[Exposed=(Window, Worker), SecureContext]
interface GPUBindGroupLayout {
};
GPUBindGroupLayout includes GPUObjectBase;

dictionary GPUBindGroupLayoutDescriptor
         : GPUObjectDescriptorBase {
    required sequence<GPUBindGroupLayoutEntry> entries;
};

dictionary GPUBindGroupLayoutEntry {
    required GPUIndex32 binding;
    required GPUShaderStageFlags visibility;

    GPUBufferBindingLayout buffer;
    GPUSamplerBindingLayout sampler;
    GPUTextureBindingLayout texture;
    GPUStorageTextureBindingLayout storageTexture;
    GPUExternalTextureBindingLayout externalTexture;
};

typedef [EnforceRange] unsigned long GPUShaderStageFlags;
[Exposed=(Window, Worker), SecureContext]
namespace GPUShaderStage {
    const GPUFlagsConstant VERTEX   = 0x1;
    const GPUFlagsConstant FRAGMENT = 0x2;
    const GPUFlagsConstant COMPUTE  = 0x4;
};

enum GPUBufferBindingType {
    "uniform",
    "storage",
    "read-only-storage",
};

dictionary GPUBufferBindingLayout {
    GPUBufferBindingType type = "uniform";
    boolean hasDynamicOffset = false;
    GPUSize64 minBindingSize = 0;
};

enum GPUSamplerBindingType {
    "filtering",
    "non-filtering",
    "comparison",
};

dictionary GPUSamplerBindingLayout {
    GPUSamplerBindingType type = "filtering";
};

enum GPUTextureSampleType {
    "float",
    "unfilterable-float",
    "depth",
    "sint",
    "uint",
};

dictionary GPUTextureBindingLayout {
    GPUTextureSampleType sampleType = "float";
    GPUTextureViewDimension viewDimension = "2d";
    boolean multisampled = false;
};

enum GPUStorageTextureAccess {
    "write-only",
    "read-only",
    "read-write",
};

dictionary GPUStorageTextureBindingLayout {
    GPUStorageTextureAccess access = "write-only";
    required GPUTextureFormat format;
    GPUTextureViewDimension viewDimension = "2d";
};

dictionary GPUExternalTextureBindingLayout {
};

[Exposed=(Window, Worker), SecureContext]
interface GPUBindGroup {
};
GPUBindGroup includes GPUObjectBase;

dictionary GPUBindGroupDescriptor
         : GPUObjectDescriptorBase {
    required GPUBindGroupLayout layout;
    required sequence<GPUBindGroupEntry> entries;
};

typedef (GPUSampler or
         GPUTexture or
         GPUTextureView or
         GPUBuffer or
         GPUBufferBinding or
         GPUExternalTexture) GPUBindingResource;

dictionary GPUBindGroupEntry {
    required GPUIndex32 binding;
    required GPUBindingResource resource;
};

dictionary GPUBufferBinding {
    required GPUBuffer buffer;
    GPUSize64 offset = 0;
    GPUSize64 size;
};

[Exposed=(Window, Worker), SecureContext]
interface GPUPipelineLayout {
};
GPUPipelineLayout includes GPUObjectBase;

dictionary GPUPipelineLayoutDescriptor
         : GPUObjectDescriptorBase {
    required sequence<GPUBindGroupLayout?> bindGroupLayouts;
};

[Exposed=(Window, Worker), SecureContext]
interface GPUShaderModule {
    Promise<GPUCompilationInfo> getCompilationInfo();
};
GPUShaderModule includes GPUObjectBase;

dictionary GPUShaderModuleDescriptor
         : GPUObjectDescriptorBase {
    required USVString code;
    sequence<GPUShaderModuleCompilationHint> compilationHints = [];
};

dictionary GPUShaderModuleCompilationHint {
    required USVString entryPoint;
    (GPUPipelineLayout or GPUAutoLayoutMode) layout;
};

enum GPUCompilationMessageType {
    "error",
    "warning",
    "info",
};

[Exposed=(Window, Worker), Serializable, SecureContext]
interface GPUCompilationMessage {
    readonly attribute DOMString message;
    readonly attribute GPUCompilationMessageType type;
    readonly attribute unsigned long long lineNum;
    readonly attribute unsigned long long linePos;
    readonly attribute unsigned long long offset;
    readonly attribute unsigned long long length;
};

[Exposed=(Window, Worker), Serializable, SecureContext]
interface GPUCompilationInfo {
    readonly attribute FrozenArray<GPUCompilationMessage> messages;
};

[Exposed=(Window, Worker), SecureContext, Serializable]
interface GPUPipelineError : DOMException {
    constructor(optional DOMString message = "", GPUPipelineErrorInit options);
    readonly attribute GPUPipelineErrorReason reason;
};

dictionary GPUPipelineErrorInit {
    required GPUPipelineErrorReason reason;
};

enum GPUPipelineErrorReason {
    "validation",
    "internal",
};

enum GPUAutoLayoutMode {
    "auto",
};

dictionary GPUPipelineDescriptorBase
         : GPUObjectDescriptorBase {
    required (GPUPipelineLayout or GPUAutoLayoutMode) layout;
};

interface mixin GPUPipelineBase {
    [NewObject] GPUBindGroupLayout getBindGroupLayout(unsigned long index);
};

dictionary GPUProgrammableStage {
    required GPUShaderModule module;
    USVString entryPoint;
    record<USVString, GPUPipelineConstantValue> constants = {};
};

typedef double GPUPipelineConstantValue; // May represent WGSL's bool, f32, i32, u32, and f16 if enabled.

[Exposed=(Window, Worker), SecureContext]
interface GPUComputePipeline {
};
GPUComputePipeline includes GPUObjectBase;
GPUComputePipeline includes GPUPipelineBase;

dictionary GPUComputePipelineDescriptor
         : GPUPipelineDescriptorBase {
    required GPUProgrammableStage compute;
};

[Exposed=(Window, Worker), SecureContext]
interface GPURenderPipeline {
};
GPURenderPipeline includes GPUObjectBase;
GPURenderPipeline includes GPUPipelineBase;

dictionary GPURenderPipelineDescriptor
         : GPUPipelineDescriptorBase {
    required GPUVertexState vertex;
    GPUPrimitiveState primitive = {};
    GPUDepthStencilState depthStencil;
    GPUMultisampleState multisample = {};
    GPUFragmentState fragment;
};

dictionary GPUPrimitiveState {
    GPUPrimitiveTopology topology = "triangle-list";
    GPUIndexFormat stripIndexFormat;
    GPUFrontFace frontFace = "ccw";
    GPUCullMode cullMode = "none";

    // Requires "depth-clip-control" feature.
    boolean unclippedDepth = false;
};

enum GPUPrimitiveTopology {
    "point-list",
    "line-list",
    "line-strip",
    "triangle-list",
    "triangle-strip",
};

enum GPUFrontFace {
    "ccw",
    "cw",
};

enum GPUCullMode {
    "none",
    "front",
    "back",
};

dictionary GPUMultisampleState {
    GPUSize32 count = 1;
    GPUSampleMask mask = 0xFFFFFFFF;
    boolean alphaToCoverageEnabled = false;
};

dictionary GPUFragmentState
         : GPUProgrammableStage {
    required sequence<GPUColorTargetState?> targets;
};

dictionary GPUColorTargetState {
    required GPUTextureFormat format;

    GPUBlendState blend;
    GPUColorWriteFlags writeMask = 0xF;  // GPUColorWrite.ALL
};

dictionary GPUBlendState {
    required GPUBlendComponent color;
    required GPUBlendComponent alpha;
};

typedef [EnforceRange] unsigned long GPUColorWriteFlags;
[Exposed=(Window, Worker), SecureContext]
namespace GPUColorWrite {
    const GPUFlagsConstant RED   = 0x1;
    const GPUFlagsConstant GREEN = 0x2;
    const GPUFlagsConstant BLUE  = 0x4;
    const GPUFlagsConstant ALPHA = 0x8;
    const GPUFlagsConstant ALL   = 0xF;
};

dictionary GPUBlendComponent {
    GPUBlendOperation operation = "add";
    GPUBlendFactor srcFactor = "one";
    GPUBlendFactor dstFactor = "zero";
};

enum GPUBlendFactor {
    "zero",
    "one",
    "src",
    "one-minus-src",
    "src-alpha",
    "one-minus-src-alpha",
    "dst",
    "one-minus-dst",
    "dst-alpha",
    "one-minus-dst-alpha",
    "src-alpha-saturated",
    "constant",
    "one-minus-constant",
    "src1",
    "one-minus-src1",
    "src1-alpha",
    "one-minus-src1-alpha",
};

enum GPUBlendOperation {
    "add",
    "subtract",
    "reverse-subtract",
    "min",
    "max",
};

dictionary GPUDepthStencilState {
    required GPUTextureFormat format;

    boolean depthWriteEnabled;
    GPUCompareFunction depthCompare;

    GPUStencilFaceState stencilFront = {};
    GPUStencilFaceState stencilBack = {};

    GPUStencilValue stencilReadMask = 0xFFFFFFFF;
    GPUStencilValue stencilWriteMask = 0xFFFFFFFF;

    GPUDepthBias depthBias = 0;
    float depthBiasSlopeScale = 0;
    float depthBiasClamp = 0;
};

dictionary GPUStencilFaceState {
    GPUCompareFunction compare = "always";
    GPUStencilOperation failOp = "keep";
    GPUStencilOperation depthFailOp = "keep";
    GPUStencilOperation passOp = "keep";
};

enum GPUStencilOperation {
    "keep",
    "zero",
    "replace",
    "invert",
    "increment-clamp",
    "decrement-clamp",
    "increment-wrap",
    "decrement-wrap",
};

enum GPUIndexFormat {
    "uint16",
    "uint32",
};

enum GPUVertexFormat {
    "uint8",
    "uint8x2",
    "uint8x4",
    "sint8",
    "sint8x2",
    "sint8x4",
    "unorm8",
    "unorm8x2",
    "unorm8x4",
    "snorm8",
    "snorm8x2",
    "snorm8x4",
    "uint16",
    "uint16x2",
    "uint16x4",
    "sint16",
    "sint16x2",
    "sint16x4",
    "unorm16",
    "unorm16x2",
    "unorm16x4",
    "snorm16",
    "snorm16x2",
    "snorm16x4",
    "float16",
    "float16x2",
    "float16x4",
    "float32",
    "float32x2",
    "float32x3",
    "float32x4",
    "uint32",
    "uint32x2",
    "uint32x3",
    "uint32x4",
    "sint32",
    "sint32x2",
    "sint32x3",
    "sint32x4",
    "unorm10-10-10-2",
    "unorm8x4-bgra",
};

enum GPUVertexStepMode {
    "vertex",
    "instance",
};

dictionary GPUVertexState
         : GPUProgrammableStage {
    sequence<GPUVertexBufferLayout?> buffers = [];
};

dictionary GPUVertexBufferLayout {
    required GPUSize64 arrayStride;
    GPUVertexStepMode stepMode = "vertex";
    required sequence<GPUVertexAttribute> attributes;
};

dictionary GPUVertexAttribute {
    required GPUVertexFormat format;
    required GPUSize64 offset;

    required GPUIndex32 shaderLocation;
};

dictionary GPUTexelCopyBufferLayout {
    GPUSize64 offset = 0;
    GPUSize32 bytesPerRow;
    GPUSize32 rowsPerImage;
};

dictionary GPUTexelCopyBufferInfo
         : GPUTexelCopyBufferLayout {
    required GPUBuffer buffer;
};

dictionary GPUTexelCopyTextureInfo {
    required GPUTexture texture;
    GPUIntegerCoordinate mipLevel = 0;
    GPUOrigin3D origin = {};
    GPUTextureAspect aspect = "all";
};

dictionary GPUCopyExternalImageDestInfo
         : GPUTexelCopyTextureInfo {
    PredefinedColorSpace colorSpace = "srgb";
    boolean premultipliedAlpha = false;
};

typedef (ImageBitmap or
         ImageData or
         HTMLImageElement or
         HTMLVideoElement or
         VideoFrame or
         HTMLCanvasElement or
         OffscreenCanvas) GPUCopyExternalImageSource;

dictionary GPUCopyExternalImageSourceInfo {
    required GPUCopyExternalImageSource source;
    GPUOrigin2D origin = {};
    boolean flipY = false;
};

[Exposed=(Window, Worker), SecureContext]
interface GPUCommandBuffer {
};
GPUCommandBuffer includes GPUObjectBase;

dictionary GPUCommandBufferDescriptor
         : GPUObjectDescriptorBase {
};

interface mixin GPUCommandsMixin {
};

[Exposed=(Window, Worker), SecureContext]
interface GPUCommandEncoder {
    GPURenderPassEncoder beginRenderPass(GPURenderPassDescriptor descriptor);
    GPUComputePassEncoder beginComputePass(optional GPUComputePassDescriptor descriptor = {});

    undefined copyBufferToBuffer(
        GPUBuffer source,
        GPUBuffer destination,
        optional GPUSize64 size);
    undefined copyBufferToBuffer(
        GPUBuffer source,
        GPUSize64 sourceOffset,
        GPUBuffer destination,
        GPUSize64 destinationOffset,
        optional GPUSize64 size);

    undefined copyBufferToTexture(
        GPUTexelCopyBufferInfo source,
        GPUTexelCopyTextureInfo destination,
        GPUExtent3D copySize);

    undefined copyTextureToBuffer(
        GPUTexelCopyTextureInfo source,
        GPUTexelCopyBufferInfo destination,
        GPUExtent3D copySize);

    undefined copyTextureToTexture(
        GPUTexelCopyTextureInfo source,
        GPUTexelCopyTextureInfo destination,
        GPUExtent3D copySize);

    undefined clearBuffer(
        GPUBuffer buffer,
        optional GPUSize64 offset = 0,
        optional GPUSize64 size);

    undefined resolveQuerySet(
        GPUQuerySet querySet,
        GPUSize32 firstQuery,
        GPUSize32 queryCount,
        GPUBuffer destination,
        GPUSize64 destinationOffset);

    GPUCommandBuffer finish(optional GPUCommandBufferDescriptor descriptor = {});
};
GPUCommandEncoder includes GPUObjectBase;
GPUCommandEncoder includes GPUCommandsMixin;
GPUCommandEncoder includes GPUDebugCommandsMixin;

dictionary GPUCommandEncoderDescriptor
         : GPUObjectDescriptorBase {
};

interface mixin GPUBindingCommandsMixin {
    undefined setBindGroup(GPUIndex32 index, GPUBindGroup? bindGroup,
        optional sequence<GPUBufferDynamicOffset> dynamicOffsets = []);

    undefined setBindGroup(GPUIndex32 index, GPUBindGroup? bindGroup,
        [AllowShared] Uint32Array dynamicOffsetsData,
        GPUSize64 dynamicOffsetsDataStart,
        GPUSize32 dynamicOffsetsDataLength);
};

interface mixin GPUDebugCommandsMixin {
    undefined pushDebugGroup(USVString groupLabel);
    undefined popDebugGroup();
    undefined insertDebugMarker(USVString markerLabel);
};

[Exposed=(Window, Worker), SecureContext]
interface GPUComputePassEncoder {
    undefined setPipeline(GPUComputePipeline pipeline);
    undefined dispatchWorkgroups(GPUSize32 workgroupCountX, optional GPUSize32 workgroupCountY = 1, optional GPUSize32 workgroupCountZ = 1);
    undefined dispatchWorkgroupsIndirect(GPUBuffer indirectBuffer, GPUSize64 indirectOffset);

    undefined end();
};
GPUComputePassEncoder includes GPUObjectBase;
GPUComputePassEncoder includes GPUCommandsMixin;
GPUComputePassEncoder includes GPUDebugCommandsMixin;
GPUComputePassEncoder includes GPUBindingCommandsMixin;

dictionary GPUComputePassTimestampWrites {
    required GPUQuerySet querySet;
    GPUSize32 beginningOfPassWriteIndex;
    GPUSize32 endOfPassWriteIndex;
};

dictionary GPUComputePassDescriptor
         : GPUObjectDescriptorBase {
    GPUComputePassTimestampWrites timestampWrites;
};

[Exposed=(Window, Worker), SecureContext]
interface GPURenderPassEncoder {
    undefined setViewport(float x, float y,
        float width, float height,
        float minDepth, float maxDepth);

    undefined setScissorRect(GPUIntegerCoordinate x, GPUIntegerCoordinate y,
                        GPUIntegerCoordinate width, GPUIntegerCoordinate height);

    undefined setBlendConstant(GPUColor color);
    undefined setStencilReference(GPUStencilValue reference);

    undefined beginOcclusionQuery(GPUSize32 queryIndex);
    undefined endOcclusionQuery();

    undefined executeBundles(sequence<GPURenderBundle> bundles);
    undefined end();
};
GPURenderPassEncoder includes GPUObjectBase;
GPURenderPassEncoder includes GPUCommandsMixin;
GPURenderPassEncoder includes GPUDebugCommandsMixin;
GPURenderPassEncoder includes GPUBindingCommandsMixin;
GPURenderPassEncoder includes GPURenderCommandsMixin;

dictionary GPURenderPassTimestampWrites {
    required GPUQuerySet querySet;
    GPUSize32 beginningOfPassWriteIndex;
    GPUSize32 endOfPassWriteIndex;
};

dictionary GPURenderPassDescriptor
         : GPUObjectDescriptorBase {
    required sequence<GPURenderPassColorAttachment?> colorAttachments;
    GPURenderPassDepthStencilAttachment depthStencilAttachment;
    GPUQuerySet occlusionQuerySet;
    GPURenderPassTimestampWrites timestampWrites;
    GPUSize64 maxDrawCount = 50000000;
};

dictionary GPURenderPassColorAttachment {
    required (GPUTexture or GPUTextureView) view;
    GPUIntegerCoordinate depthSlice;
    (GPUTexture or GPUTextureView) resolveTarget;

    GPUColor clearValue;
    required GPULoadOp loadOp;
    required GPUStoreOp storeOp;
};

dictionary GPURenderPassDepthStencilAttachment {
    required (GPUTexture or GPUTextureView) view;

    float depthClearValue;
    GPULoadOp depthLoadOp;
    GPUStoreOp depthStoreOp;
    boolean depthReadOnly = false;

    GPUStencilValue stencilClearValue = 0;
    GPULoadOp stencilLoadOp;
    GPUStoreOp stencilStoreOp;
    boolean stencilReadOnly = false;
};

enum GPULoadOp {
    "load",
    "clear",
};

enum GPUStoreOp {
    "store",
    "discard",
};

dictionary GPURenderPassLayout
         : GPUObjectDescriptorBase {
    required sequence<GPUTextureFormat?> colorFormats;
    GPUTextureFormat depthStencilFormat;
    GPUSize32 sampleCount = 1;
};

interface mixin GPURenderCommandsMixin {
    undefined setPipeline(GPURenderPipeline pipeline);

    undefined setIndexBuffer(GPUBuffer buffer, GPUIndexFormat indexFormat, optional GPUSize64 offset = 0, optional GPUSize64 size);
    undefined setVertexBuffer(GPUIndex32 slot, GPUBuffer? buffer, optional GPUSize64 offset = 0, optional GPUSize64 size);

    undefined draw(GPUSize32 vertexCount, optional GPUSize32 instanceCount = 1,
        optional GPUSize32 firstVertex = 0, optional GPUSize32 firstInstance = 0);
    undefined drawIndexed(GPUSize32 indexCount, optional GPUSize32 instanceCount = 1,
        optional GPUSize32 firstIndex = 0,
        optional GPUSignedOffset32 baseVertex = 0,
        optional GPUSize32 firstInstance = 0);

    undefined drawIndirect(GPUBuffer indirectBuffer, GPUSize64 indirectOffset);
    undefined drawIndexedIndirect(GPUBuffer indirectBuffer, GPUSize64 indirectOffset);
};

[Exposed=(Window, Worker), SecureContext]
interface GPURenderBundle {
};
GPURenderBundle includes GPUObjectBase;

dictionary GPURenderBundleDescriptor
         : GPUObjectDescriptorBase {
};

[Exposed=(Window, Worker), SecureContext]
interface GPURenderBundleEncoder {
    GPURenderBundle finish(optional GPURenderBundleDescriptor descriptor = {});
};
GPURenderBundleEncoder includes GPUObjectBase;
GPURenderBundleEncoder includes GPUCommandsMixin;
GPURenderBundleEncoder includes GPUDebugCommandsMixin;
GPURenderBundleEncoder includes GPUBindingCommandsMixin;
GPURenderBundleEncoder includes GPURenderCommandsMixin;

dictionary GPURenderBundleEncoderDescriptor
         : GPURenderPassLayout {
    boolean depthReadOnly = false;
    boolean stencilReadOnly = false;
};

dictionary GPUQueueDescriptor
         : GPUObjectDescriptorBase {
};

[Exposed=(Window, Worker), SecureContext]
interface GPUQueue {
    undefined submit(sequence<GPUCommandBuffer> commandBuffers);

    Promise<undefined> onSubmittedWorkDone();

    undefined writeBuffer(
        GPUBuffer buffer,
        GPUSize64 bufferOffset,
        AllowSharedBufferSource data,
        optional GPUSize64 dataOffset = 0,
        optional GPUSize64 size);

    undefined writeTexture(
        GPUTexelCopyTextureInfo destination,
        AllowSharedBufferSource data,
        GPUTexelCopyBufferLayout dataLayout,
        GPUExtent3D size);

    undefined copyExternalImageToTexture(
        GPUCopyExternalImageSourceInfo source,
        GPUCopyExternalImageDestInfo destination,
        GPUExtent3D copySize);
};
GPUQueue includes GPUObjectBase;

[Exposed=(Window, Worker), SecureContext]
interface GPUQuerySet {
    undefined destroy();

    readonly attribute GPUQueryType type;
    readonly attribute GPUSize32Out count;
};
GPUQuerySet includes GPUObjectBase;

dictionary GPUQuerySetDescriptor
         : GPUObjectDescriptorBase {
    required GPUQueryType type;
    required GPUSize32 count;
};

enum GPUQueryType {
    "occlusion",
    "timestamp",
};

[Exposed=(Window, Worker), SecureContext]
interface GPUCanvasContext {
    readonly attribute (HTMLCanvasElement or OffscreenCanvas) canvas;

    undefined configure(GPUCanvasConfiguration configuration);
    undefined unconfigure();

    GPUCanvasConfiguration? getConfiguration();
    GPUTexture getCurrentTexture();
};

enum GPUCanvasAlphaMode {
    "opaque",
    "premultiplied",
};

enum GPUCanvasToneMappingMode {
    "standard",
    "extended",
};

dictionary GPUCanvasToneMapping {
  GPUCanvasToneMappingMode mode = "standard";
};

dictionary GPUCanvasConfiguration {
    required GPUDevice device;
    required GPUTextureFormat format;
    GPUTextureUsageFlags usage = 0x10;  // GPUTextureUsage.RENDER_ATTACHMENT
    sequence<GPUTextureFormat> viewFormats = [];
    PredefinedColorSpace colorSpace = "srgb";
    GPUCanvasToneMapping toneMapping = {};
    GPUCanvasAlphaMode alphaMode = "opaque";
};

enum GPUDeviceLostReason {
    "unknown",
    "destroyed",
};

[Exposed=(Window, Worker), SecureContext]
interface GPUDeviceLostInfo {
    readonly attribute GPUDeviceLostReason reason;
    readonly attribute DOMString message;
};

partial interface GPUDevice {
    readonly attribute Promise<GPUDeviceLostInfo> lost;
};

[Exposed=(Window, Worker), SecureContext]
interface GPUError {
    readonly attribute DOMString message;
};

[Exposed=(Window, Worker), SecureContext]
interface GPUValidationError
        : GPUError {
    constructor(DOMString message);
};

[Exposed=(Window, Worker), SecureContext]
interface GPUOutOfMemoryError
        : GPUError {
    constructor(DOMString message);
};

[Exposed=(Window, Worker), SecureContext]
interface GPUInternalError
        : GPUError {
    constructor(DOMString message);
};

enum GPUErrorFilter {
    "validation",
    "out-of-memory",
    "internal",
};

partial interface GPUDevice {
    undefined pushErrorScope(GPUErrorFilter filter);
    Promise<GPUError?> popErrorScope();
};

[Exposed=(Window, Worker), SecureContext]
interface GPUUncapturedErrorEvent : Event {
    constructor(
        DOMString type,
        GPUUncapturedErrorEventInit gpuUncapturedErrorEventInitDict
    );
    [SameObject] readonly attribute GPUError error;
};

dictionary GPUUncapturedErrorEventInit : EventInit {
    required GPUError error;
};

partial interface GPUDevice {
    attribute EventHandler onuncapturederror;
};

typedef [EnforceRange] unsigned long GPUBufferDynamicOffset;
typedef [EnforceRange] unsigned long GPUStencilValue;
typedef [EnforceRange] unsigned long GPUSampleMask;
typedef [EnforceRange] long GPUDepthBias;

typedef [EnforceRange] unsigned long long GPUSize64;
typedef [EnforceRange] unsigned long GPUIntegerCoordinate;
typedef [EnforceRange] unsigned long GPUIndex32;
typedef [EnforceRange] unsigned long GPUSize32;
typedef [EnforceRange] long GPUSignedOffset32;

typedef unsigned long long GPUSize64Out;
typedef unsigned long GPUIntegerCoordinateOut;
typedef unsigned long GPUSize32Out;

typedef unsigned long GPUFlagsConstant;

dictionary GPUColorDict {
    required double r;
    required double g;
    required double b;
    required double a;
};
typedef (sequence<double> or GPUColorDict) GPUColor;

dictionary GPUOrigin2DDict {
    GPUIntegerCoordinate x = 0;
    GPUIntegerCoordinate y = 0;
};
typedef (sequence<GPUIntegerCoordinate> or GPUOrigin2DDict) GPUOrigin2D;

dictionary GPUOrigin3DDict {
    GPUIntegerCoordinate x = 0;
    GPUIntegerCoordinate y = 0;
    GPUIntegerCoordinate z = 0;
};
typedef (sequence<GPUIntegerCoordinate> or GPUOrigin3DDict) GPUOrigin3D;

dictionary GPUExtent3DDict {
    required GPUIntegerCoordinate width;
    GPUIntegerCoordinate height = 1;
    GPUIntegerCoordinate depthOrArrayLayers = 1;
};
typedef (sequence<GPUIntegerCoordinate> or GPUExtent3DDict) GPUExtent3D;